iPhone Calendar search does not produce all valid items

When I search my iPhone calendar for a term that is in numerous calendar entries (e.g. 'Cardiac' or 'Chauhan'), I get either partial results (e.g. an entry for today) or no results on my iPhone. This happened on my iPhone 12 Pro with iOS 18, and it continues on my new iPhone 16 Pro with iOS 18. Pretty frustrating when I am trying to add a new entry for an irregularly occurring event (e.g. 'Rolfing') or to find an old or future appointment. I'm not 100% sure, but I think it started happening when I moved to iOS 18

The same calendar searches on my Macbook Pro (2018; latest OS) produce numerous results that seem complete.

I'm on iCloud with plenty of storage, I have killed and relaunched Calendar App, restarted iphone, confirmed all calendars are checked and unhid, set Calendar to 'Sync all events', etc. I have done many of these actions multiple times.

I just found two links with a solution that fixed the issue - but this is a clear BUG that needs to be fixed - there are thousands of users impacted. Please reply with plans for a REAL fix.

Why am I getting zero results when search… - Apple Community

Calendar Search not working on iPhone - Apple Community

This last link shows multiple versions of the same issue, with 20000+ views / me toos