My first assumption here is that your comment listing mode is set to Local instead of All. Try visiting a post and opening the sorting menu at the top right and making sure All is selected. When the listing mode is set to local, only comments from your instance will load. This would make sense being as the behavior goes away when reinstalling the app, and your settings are reset.
If that doesn’t resolve the issue, please let me know and I will look into what may be happening here.
Please note that when you switch to guest mode, your listing mode is reset to Local, I’ll update this behavior in the next release.