@MichaelSchoenitzer I was checking the issue in wikidata.org (1.31.0-wmf.15 ). Without beta-feature "New filters for edit review", I enabled "Expand watchlist to show all changes, not just the most recent" and there are all changes displayed:

I disabled "Expand watchlist to show all changes, not just the most recent" - and only the most recent change is displayed:

Can you re-check again? Make sure that no other options are checked in Preferences-Watchlist (e.g. 'Hide edits by logged in users from the watchlist' ).

Task is stalled until @MichaelSchoenitzer replies.

@Etonkovidova & @Trizek-WMF: I debugged a bit. When enabling the beta-feature "New filters for edit review" the url of the watchlist gets additional arguments. Without the beta-feature the url of the watchlist is:
https://www.wikidata.org/wiki/Special:Watchlist
With the beta-feature the url reads like:
https://www.wikidata.org/wiki/Special:Watchlist?hidemyself=1&hidebots=1&hidecategorization=1&limit=250&days=7&enhanced=1&urlversion=2

When you disable the beta-feture again but don't change the url – i.e. you reload the already open page instead of clicking on "watchlist" in the menu – the enhanced watch list does not work anymore.
This is especially an issue when you if you never close your watchlist but keep it open in a tab or have set a bookmark (while the beta-feature was enabled).

Thank you, @MichaelSchoenitzer - this issue (especially bookmarking the Watchlist) certainly needs to be addressed. I am moving the task to `Collaboration -Team-Triage (Collab-Team-This-Quarter)' board.

In T184174#3887784, @MichaelSchoenitzer wrote:

When you disable the beta-feture again but don't change the url – i.e. you reload the already open page instead of clicking on "watchlist" in the menu – the enhanced watch list does not work anymore.
This is especially an issue when you if you never close your watchlist but keep it open in a tab or have set a bookmark (while the beta-feature was enabled).

Just trying to pinpoint the exact problem -- is the "enhanced" list not working at all (so, you can't change to it) or does it "just" load it initially as the wrong preference, but you're able to change it afterwards?

The issue is not specific to wikidata. In a sense, it's logical - page specific "Group results by page" option will not be preserved when a user opts out of the new filters.

"New filters for edit review" beta feature is enabled; Preferences-Recent changes "Group changes by page in recent changes and watchlist" not enabled. Watchlist page filter option "Group results by page" is enabled.

https://en.wikipedia.beta.wmflabs.org/wiki/Special:Watchlist?limit=250&days=30&enhanced=1&urlversion=2

The above url was bookmarked. Then, the user opts out from "New filters for edit review" beta feature and loads bookmarked ulr:

The 'group results by page' option works by the preference but also by the URL parameter. In the new RC system, we make the URL parameter be synchronized with the preference -- so it seems like it's the same. The old system doesn't have that synchronization, though, which means that whatever preference the user has for "group by page" will be overridden by the enhanced=xx parameter.

This is expected behavior. If you save the URL from the "new" system where more data is produced, and then you use the same URL in the old system, it will use the data that was saved -- including whether or not you had the "group by page" selected.

The 'group results by page' option works by the preference but also by the URL parameter. In the new RC system, we make the URL parameter be synchronized with the preference -- so it seems like it's the same. The old system doesn't have that synchronization, though, which means that whatever preference the user has for "group by page" will be overridden by the enhanced=xx parameter.

But that's apparently not what happens. No matter what the value of enhanced in the url is, and also when you remove the url-praramerter enhanced, you will all ways get the output without all edits.

@Mooeypoo enhanced=1 controls "group by page", it doesn't control whether the WL shows only the most recent edit for each page, or all edits, and that's what he's talking about.

In T184174#3894570, @Catrope wrote:

@Mooeypoo enhanced=1 controls "group by page", it doesn't control whether the WL shows only the most recent edit for each page, or all edits, and that's what he's talking about.

I may have misunderstood, then. I understood we're talking about "enhanced" (group by pages) from this comment:

In T184174#3887784, @MichaelSchoenitzer wrote:

When you disable the beta-feture again but don't change the url – i.e. you reload the already open page instead of clicking on "watchlist" in the menu – the enhanced watch list does not work anymore.

Did I misunderstand?

In T184174#3894615, @Mooeypoo wrote:

In T184174#3887784, @MichaelSchoenitzer wrote:

When you disable the beta-feture again but don't change the url – i.e. you reload the already open page instead of clicking on "watchlist" in the menu – the enhanced watch list does not work anymore.

Did I misunderstand?

I think he may have confused the terms "enhanced" and "expanded".

@Catrope yes, sorry for the confusion - first I too thought that the issue was about enhanced=1 The problem seems to be that "Expand watchlist..." option is not saved in a bookmark when new filters are enabled. Without filters the "Expand watchlist..." can be bookmarked.

tl; dr

I rechecked the straightforward scenario:

1. Without new filters (the beta feature) enabled, I enabled the option "Expand watchlist to show all changes, not just the most recent" in Preferences-Watchlist.

So I see the results. Notice the results are not grouped for 'Mavetuna' cause - it's only expanded to show all changes.

2. Enable the new filters and click on Watchlist: https://en.wikipedia.beta.wmflabs.org/wiki/Special:Watchlist?hideWikibase=1&limit=250&days=30&urlversion=2 "Expand watchlist to show all changes, not just the most recent" will not be reflected in url, but the UI will be displayed correctly:

3. Bookmark it.

4. Disable the new filters - and click on the bookmarked link. Only one record will be displayed - "Expand watchlist..." option was not saved in the bookmark.

3. Reload the page - "Expand watchlist..." will take effect again.

@Etonkovidova: thanks for explaining it this good! This is exactly what was my issue.

I am changing the title of the ticket and updating the content since the issue is not specific to Wikidata and Expanded watchlist option.