This is not surprising at all. I beta tested for them for some time when the app came out- and up until it became subscription last year (which I dont agree with their model after people paid for the app outright).
Not being able to reach them is not surprising. Even on their private Slack for beta tester they often never addressed comments about features or bugs; you were lucky if you ever got a reply. I cant figure out why have beta testers if you never listened to the bugs or comments ?♂️
Half the stuff in the app has always been broken or buggy despite charging money for it; and then monthly at that. I just cant agree with that ethically so I deleted the app/testflight and stopped dealing with them.
If it was a fully 98%+ working app then sure, no app has no bugs. But it's always been in beta form really and for a paid app thats not acceptable; especially when people report the issues and they go ignored.
It is certainly the most powerful 3rd party app out there by a long mile, but the most buggy too as it never gets the attention it needs ground up. And no, this isnt to bash them either; its actually sad because the app has the potential to be the most "desktop Outlook does it all power user" app, every other one is trying to be Mailbox or Google Inbox basic consumer features, but none of the issues have ever been fixed. It needs a top to bottom rewrite frankly and address all bug rather than cramming in more features that are half-baked.