[Arnavion]

It absolutely has not. I'm looking at messages in Element X right now that don't decrypt, ie "Waiting for this message", from one user interspersed between decrypted messages from other users. Meanwhile my other two clients (app.element.io and pantalaimon) happen to be able to read all of them.

[eredengrin]

This is quite rare but it did happen to me (exactly) once. Report it as a bug, they put very high priority on unable to decrypt reports and my issues stopped happening within a few days (can't promise that is always the result since I don't know what happens behind the scenes, but it won't hurt, and reporting bugs from within the app is pretty straightforward - hit the username icon at top left to get to settings, then "Report a problem").