I have been using DAVx5 for a while, and have never encountered this issue before. Except for enabling the new dark mode (thank you so much!), I haven’t made any configuration changes. I did update to v3.3.11-ose. The new version seemed to work fine for at least a week. I’m not sure what to do now besides delete all data in the app and try to remember how I had it configured.
The symptom DAVx5 is experiencing is that a white screen (with the normal Android status bar) appears instead of the UI. As mentioned above, I’m using the new dark theme, and so seeing an all white screen could possibly be indicative that the DAVx5 UI isn’t loading at all or an issue with the new dark theme.
I have had a similar problem using DAVx5 since dark mode was introduced except that in my case initially the blank screen was dark. My phone (realme 7 pro, android 10) uses a system-wide Dark theme and I was trying to use DAVx’s Light theme. I could only get around the problem by enabling Light mode on my phone and making sure that I either enabled ‘system default’ in DAVx’s theme settings or used a theme to match that enabled on my phone (light or dark as appropriate). DAVx appears to have a problem with forcing its own light theme when dark mode is enabled system-wide and vice versa. You may be experiencing the same problem on your device.