from the report:

• a) {{<ref>source a</ref>}} -> eats ref completely

in all other reported cases:

• b) {<ref>source b</ref>}
• c) {{<ref>source c</ref>
• d) {<ref>source d</ref>
• e) {{<ref>source a</ref>}.

VE tells the user once "This is Wikitext" but then carries on; see test page:

https://de.wikipedia.org/w/index.php?title=Benutzerin:Miss-Sophie/Spielwiese&oldid=122231700

Chances are this issue is systemic; three more examples:

1. Info box for movie articles:

https://de.wikipedia.org/wiki/Vorlage:Infobox_Film

includes three refs in

https://de.wikipedia.org/wiki/Shine_a_Light

and they all get eaten if the entry is loaded in VE.

2. Info box for corporate entities:

https://de.wikipedia.org/wiki/Vorlage:Infobox_Unternehmen

see the first four refs in

https://de.wikipedia.org/wiki/Sony

3. https://de.wikipedia.org/wiki/Vorlage:Infobox_Chemikalie

eats the two included refs in:

https://de.wikipedia.org/wiki/Magnesiumcarbonat

This looks like a side effect of the underlying problem in bug 50474.

Updates:

Rolling Stones: The section Discografie

https://de.wikipedia.org/wiki/The_Rolling_Stones#Diskografie

includes another article inserted as template:

https://de.wikipedia.org/wiki/The_Rolling_Stones/Disko-_und_Videografie

However, the article isn't displayed in full but only relevant parts, picked by onlyinclude-tags.

Shine a Light: The issue not included in a template is caused by something VE apparently can't handle in spelling out the ref name but Wikicode can: "_" vs " ":

https://de.wikipedia.org/w/index.php?title=Shine_a_Light&diff=prev&oldid=122747897

The other two are eaten by the template, i.e. the same source is also referred to in refs outside the template and VE simply doesn't count the template-inserted refs.

Merging this with bug 50474 which I have managed to determine that this is the same as that.

• This bug has been marked as a duplicate of bug 50474 ***