Cannot enable overrides for any bundle if another bundle has full view mode enabled

@tim.plunkett I installed a fresh site locally and was able to get this to work without issue just as you described.

I went back to the site with which I'm having issues to see wha's going on. I checked inthe LayoutBuilderEntityViewDisplayForm.php file and verified my menu's mode via $this->entity->getMode(). It returns "default". However, $this->isCanonicalMode($this->entity->getMode()) is returning false.

I looked further into isCanonicalMode(), specifically the following query:

 $query = $this->entityTypeManager->getStorage($this->entity->getEntityTypeId())->getQuery()
        ->condition('status', TRUE)
        ->condition('mode', $canonical_mode);
      return !$query->count()->execute();

This query is returning the 'full' view mode of an unrelated content type:

array:1 [
  "node.content_type.full" => "node.content_type.full"
]

This doesn't seem to be correct but I'm not sure what might be causing this.

I applied the patch in #5 and it resolves the issue with menu links. The option to allow each entity of the given type to have its layout customized now shows up as expected. When that option is checked I've verified that the "Layout" tab is available, too.

I noticed while testing that this issue was occurring in various content types in addition to the menu link issues. It's working as expected for those content types as well.