"Linux: Instrument not working correctly/constantly disconnecting (conflict with libmtp)
Solution: There is a bug on some systems with libmtp that causes instruments to continuously switch between connected and disconnected state. This seems to be a bug in libmtp-runtime. You can work around it by renaming /lib/udev/mtp-probe or updating to libmtp 1.0.6 where the issue should be fixed."
Ah. From dispcalGUI documentation:
"Linux: Instrument not working correctly/ constantly disconnecting (conflict with libmtp)
Solution: There is a bug on some systems with libmtp that causes instruments to continuously switch between connected and disconnected state. This seems to be a bug in libmtp-runtime. You can work around it by renaming /lib/udev/mtp-probe or updating to libmtp 1.0.6 where the issue should be fixed."