Re: Sorry, I can't. It's confidential.
If we can't reproduce an issue then we can't fix it.
Re: Moreover, I'm not a fan of the new UI for events.
There is no new UI for events.
Re: It used to show the choices to accept, decline, etc. Right in the body of the emailed invitation, you could see it in the day's events, choose your option, then decide whether or not to send a reply, and it would automatically delete the invite email. I now have to open the .ics file to see anything. Why the extra steps?
Two possibilities:
1 - Your account used to be set up in Aqua Mail as Exchange type (the UI mimics Outlook, including "delete after accept"), and now it's set up as IMAP (which doesn't provide calendar sync, so you get .ics attachments)
2 - It's still set up as Exchange, but the original event for some reason cannot be found by the app on the server.
Re: when someone sent an updated invitation
Still works same way actually.
Yes I understand that "something's changed for you" -- other than what I wrote above, if you re-installed the app, please check that it has the Calendar permission (phone settings -> apps -> tap into Aqua Mail -> check Permissions).