mobile_scanner (CameraX) on MediaTek MT6761 / Android 9: camera starts but no frames after app is force-stopped, until reboot

I'm building an inventory app in Flutter that scans barcodes with the rear camera using mobile_scanner (CameraX backend) on a rugged PDA (Symphony M1, MediaTek MT6761, Android 9). It works at first, but after I force-sto