If the user opens a collapsed element, all [show] links in the element change to [hide], including the toggle links of nested collapsible elements (code; example—try to close and reopen the outer navbox). It's very confusing as it seems like the nested table has no content. Nested collapsible elements should be excluded from the jQuery selection.
Example: https://en.wikipedia.org/wiki/User:Jdlrobson/T186978
This seems to be about the Template:Navbox which invokes Module:Navbox?
(Wondering myself: Is this actually part of some MediaWiki code repository, or is that code which is entirely maintained on-wiki only?)
This particular template uses {{navbox}} (which doesn't use Lua on huwiki yet), but looking at the code, it should effect any other collapsible elements using mw-collapsible class (MediaWiki core).
Change 431984 had a related patch set uploaded (by TheDJ; owner: TheDJ):
[mediawiki/core@master] makeCollapsible: fix state of nested collapsibles
Change 431984 merged by jenkins-bot:
[mediawiki/core@master] makeCollapsible: fix state of nested collapsibles
Change 433621 had a related patch set uploaded (by TheDJ; owner: TheDJ):
[mediawiki/core@master] makeCollapsible: Add test for nested collapsibles
Change 433621 merged by jenkins-bot:
[mediawiki/core@master] makeCollapsible: Add test for nested collapsibles