I have ~50 communities subscribed, none of them are empty, and when I use a desktop site, the subscribed feed loads fine. However when I use sync, it loads no posts and I get the message "this community has no posts" (as in the screenshot). I also have an alt account that doesn't have this problem. It kind of kills the app's usefulness for this account. I'm confused and not sure what to do about it.
I've noticed it happening to one of my instances but not my other. I agree with your assessment though.