They're stored in the Documents folder so iOS should absolutely not treat them as cache files which can be removed.

There is no maximum number, they are simply files stored on the device. I don't think we've ever had a report of them disappearing. That basically means iOS is removing random files from the filesystem, which sounds unlikely. There is no scenario under which SkyDemon will delete an aircraft file except the explicit user action to delete one. I assume they all have very unique names and registrations?

Is there a maximum limit to the number of aircraft profiles you can have stored on the iPad?

I have 12 at the moment covering various types and registrations, but every now and then, one of them will disappear from my device, forcing me to "Open from Cloud", which is really annoying. An even worse scenario is when one profile wasn't backed up to cloud storage and then disappears. I haven't been able to identify a trend yet or timescales - it seems random.

So, whats causing aircraft profiles to disappear?

Cheers