I think I see what happened, your search preferences got saved locally as explicitly null when they ought to be created anew if that happens.
I would take these steps, stopping if any of them work.:
1. Log out of the app, fully close (dismiss, force close, etc). Restart it, log back in.
2. Clear local app data (Android: Settings -> Apps & notifications -> M3E -> Storage & cache -> Clear storage / Clear cache). Restart app.
3. Uninstall & Reinstall.
One of those should work. On my end I'll see if I can add a check protecting against this.