Please check the following:
1) If you recently updated DigiCal or Android you might need to restart your phone first to get it working (by the way, if you are using a DigiCal version below v1.6.3 please update to the newest version of DigiCal.).
2) Do you have developer options enabled in your phone's settings menu? If so please disable it, then remove and re-add the widget back again.
3) Please try another launcher such as Solo Launcher to double check if you have the same issue and let me know: https://play.google.com/store/apps/details?id=home.solo.launcher.free&hl=en
Widgets are drawn by the launcher so many widget issues can be quite complicated to solve.
4) Make sure you add us (and any custom launcher) to the exceptions list of any task killer apps or battery saving system settings. Some phones may have multiple settings screens where you need to do the whitelisting, and some manufacturers may reset your settings after major system updates. This page includes some hints on where to start looking: https://dontkillmyapp.com/
*We've got quite a few tickets from users after updating to Android 9 having widget issues but so far these steps have worked for most of them. If you are still having problems getting the widget to work we're not sure at the moment what else could be causing this but some other things you can try is to remove/re-add the widget, change the wallpaper, add us to the whitelist of any data saving features, add a 2nd or 3rd widget on a new homescreen without removing the original frozen widget, or to re-install the app (though that last one will reset your app settings).