• Did you bypass your browser cache and does it still happen afterwards?
• Is this fully reproducible?
• I assume "Categorization entries" means https://he.wikipedia.org/w/index.php?title=%D7%9E%D7%99%D7%95%D7%97%D7%93:%D7%A9%D7%99%D7%A0%D7%95%D7%99%D7%99%D7%9D_%D7%90%D7%97%D7%A8%D7%95%D7%A0%D7%99%D7%9D&hideWikibase=0&hidecategorization=0 ? Cannot reproduce, (הבדל | היסטוריה) are links in Firefox 49.

Well, @Aklapper, yes, yes, yes, and FF.49.0.1

Hmm, why is your screenshot Left-To-Right (LTR) while he.wp is RTL? If you have specific settings in your preferences that might influence reproducing the problem, please share them in bug reports.

No, @Aklapper, I just used uselang=en so you can read it.

Hi, @Aklapper. I choosed in different account, without any gadgets or non default preferences or local js or css files - the same problem.

1. I am logged in, using Firefox 49, and use the Vector skin.
2. I manually enabled "Group changes by page in recent changes and watchlist" on https://he.wikipedia.org/wiki/מיוחד:העדפות?uselang=en#mw-prefsection-rc . "Hide categorization of pages" was already enabled by default.
3. I went to https://he.wikipedia.org/w/index.php?title=מיוחד:שינויים_אחרונים&hideWikibase=0&hidecategorization=0&uselang=en
4. What I see:

5. This looks very different from your screenshot, for reasons that I do not know and need to be found out:

A list of exact steps, environment, and settings to reproduce is extremely welcome.

@Aklapper, you are on the wrong page. It's watchlist, not recent changes. See the task title.

Ah, thanks! The sentence "I always use grouping mode for watchlist and recent changes in preferences" tricked me, so I thought I can see it on both pages. My fault.

https://he.wikipedia.org/w/index.php?title=מיוחד:העדפות&uselang=en#mw-prefsection-watchlist does not show any option related to "grouping mode" hence I still do not know how to reproduce your view.

A numbered list of steps to reproduce that others can just follow is very welcome.

1. Open recent changes properties, #Aklapper.
2. Turn on the first advanced feature - grouping mode fot recent changes and watchlist.
3. Open Special:Watchlist.
4. If Hide categorization radiobox in checked, uncheck it and click list rebuild button.
5. And then check it again with the grouping mode in 1 turned off.

@Aklapper, I checked in recent changes - same problem. I added in enwiki, where I do not work usually - same problem.

Thanks! (For future reference, links are welcome :) )
Hmm, I'm afraid I cannot reproduce:

1. I go to https://he.wikipedia.org/w/index.php?title=%D7%9E%D7%99%D7%95%D7%97%D7%93:%D7%94%D7%A2%D7%93%D7%A4%D7%95%D7%AA&uselang=en#mw-prefsection-rc
2. Under "Advanced options", I enable "Group changes by page in recent changes and watchlist". I leave the three other options unchecked.
3. I go to https://he.wikipedia.org/wiki/%D7%9E%D7%99%D7%95%D7%97%D7%93:%D7%A8%D7%A9%D7%99%D7%9E%D7%AA_%D7%94%D7%9E%D7%A2%D7%A7%D7%91?uselang=en
4. I disable "page categorization"
5. I click the "Show" button (which ignores that I added uselang=en to the URL earlier)
6. I get this result:

Hi, @Aklapper, once again:
the plain text is in nongrouping mode. I gave it to you to compare, but the problem is when "2"in your list is disabled.
There is no categorization in the watchlist you showed me. You need bigger watchlist, that has many categories. Try adding to your watchlist this category, it has 4 entries today, or this one, ut has 3 entries today.

...and after performing step 5 "And then check it again with the grouping mode in 1 turned off." in T148533#2736348, the result here is:

Agauin, it's without categorization entries, @Aklapper. Star these two categories and refresh.

Okay, I can reproduce, but what would you expect "diff" and "history" to actually link to?

Great, @Aklapper. The same as in grouping mode, they work there. Try this category, it has one categorization entry today, so you'll see the links.

So as far as I can tell (from what I read above)

Per https://phabricator.wikimedia.org/T109688#1593043 the links were disabled when CatWatch was initially introduced.

My comment says this is essentially pending deciding what to link to.

I checked the steps described above - it does not make sense to have diff|history as plain text on Watchlist and as links, e.g. on Special:Related changes.

Watchlist-plain text	Related changes-links