Worth separating two things that both get called "the index" here, because you will get contradictory advice otherwise.
The content index — mail, messages, files, anything inside an app — genuinely does rebuild on its own, genuinely can take hours after a large update, and genuinely does behave better after a night plugged in and on wifi. If your problem were that one, waiting would have fixed it.
What you have described is not that one. Your ordinary search results are fine. Only the app-declared actions are missing. Those are two different mechanisms that happen to appear in the same list on screen, which is a UI decision that has cost a lot of people a lot of evenings.
So you can stop waiting. Waiting is the right treatment for the other illness.