Your hinting for array keys work only when I write the quotes for the first time, for example I have array $validatedData, I have annotation for that array and if I write:
$validatedData[]
and then I type quotes:
$validatedData['']
hint appears with proper keys, but if I click somewhere else and come back and force to open hint (in my case ctrl+ space), then only some very generic works appears and i must to delete the quotes and retype them to have proper hint again.