How do I fix Calendar search not working with alerts on iPhone 16 Pro?

The calendar search isn’t working properly on my iPhone 16 Pro. At first I thought it was specific calendars, then whether the entry was all day or time-specific, or a past and/or repeating event, but it’s beginning to look as if it’s got something to do with having an alert set up on them. Obviously I want alerts on some things plus I had a situation today where I needed to check a past appointment which had required an alert, so I hope there’s a solution somewhere! (Late edit: I chose one event with an alert to experiment on. I searched, it didn’t come up, I took the alert off, it came up, put the alert back on, searched again, and up it came again! I give up!)

I’ve done the usual (restart, update etc) and I don’t have the same problem on my iPad. I’ve searched other threads but no-one else seems to be having this specific issue.

To be honest I’ve had loads of problems with various features not working properly since I bought this phone - my husband bought one at exactly the same time and he hasn’t had any of the issues I have!

[Re-Titled by Moderator]