@Aklapper I tend to think the problem is real but maybe has been wrongly reported.

VisualEditor API output is a bit combersome but if you look at the REST API https://li.wiktionary.org/api/rest_v1/page/html/Wiktionary:Veurblaad you clearly see the big boxes missing in the second half of the page in comparison with online version https://li.wiktionary.org/wiki/Wiktionary:Veurblaad.

Should I better open a new ticket? Or would you agree to reopen it?

@Kelson: Hmm... I'd say better to open a new ticket - thanks in advance! :)

There is a stray <noinclude> on that page. If that is removed, this will get fixed.

....
|-<noinclude> 
|- <!------------ Rij twee: Overzicht // Index ------------->
....

We may not fix this edge case issue in Parsoid any time soon. So, my recommendation would be to get that <noinclude> deleted.

@ssastry Thank you very much for the analysis.

Remarks:

• If fixing the wikicode is the quickest way to solve the problem, I'm happy to follow it. But I don't have the permissions to edit this main page. I left a message on the talk page, hopefully someone will be able to fix it. See https://li.wiktionary.org/w/index.php?title=Euverl%C3%A8k_Wiktionary:Veurblaad&section=3
• That said, <noinclude> should not apply here as the page is not transcluded I believe. It seems from your comment that you agree on that. As such I plan to open a ticket. The question of when it will be fixed is another topic and I would prefer to not avoid opening a ticket based on this consideration.
• Finally, I probably misundestand the nature of the problem, but this seems not really an edge case, I strongly suspect I have on MWoffliner side other tickets which might been cause by this bug.

Someone has fixed the problem in the wiki source at https://li.wiktionary.org/w/index.php?title=Wiktionary%3AVeurblaad&type=revision&diff=645102&oldid=628893.

It works fine now.

I have tried to open a dedicated ticket but I don't achieve to create a simple reproduction case (probably because I don't fully understand the bug). Therefore I won't open one, but I still believe this shoudl be tracked.

In T227851#6712062, @Kelson wrote:

• That said, <noinclude> should not apply here as the page is not transcluded I believe. It seems from your comment that you agree on that. As such I plan to open a ticket. The question of when it will be fixed is another topic and I would prefer to not avoid opening a ticket based on this consideration.

Strictly speaking, that is true. But, the matter is complicated by Parsoid's template-wrapping code and fostered-content detection code. I suspect what is going on here is truly an edge case where the <noinclude> in a fostered content position messes up other behavior. So, it was simpler to just fix that wikitext and not bother adding additional logic in Parsoid.

Accordingly, I am going to mark this resolved. Let us revisit this issue via a new ticket if this shows up in other scenarios in the future rather than keep this open when, in reality, we are unlikely to investigate this corner case (there is far too much on our plate right now).