I managed to solve this issue (at least, 10 times out of 10 it workes so... I guess?).
All I did was to manually modify the PHP file located at this folder:
$ROOT/vendor/flarum/tags/src/Content/Tags.php
Inside the PHP file, there is the last function that should look like this:
private function getTagsDocument(Request $request)
{
return json_decode($this->api->withParentRequest($request)->withQueryParams([
'include' => 'children,lastPostedDiscussion'
])->get('/tags')->getBody(), true);
}
I managed to solve this issue adding ",parent" after the include as following:
private function getTagsDocument(Request $request)
{
return json_decode($this->api->withParentRequest($request)->withQueryParams([
'include' => 'children,lastPostedDiscussion,parent'
])->get('/tags')->getBody(), true);
}
Many thanks to @SychO for having pointed it out on GitHub
