MIDI doesn't work

I have an e-drum (Millenium MPS-850) which sends MIDI information (checked with MIDI-OX).
My Cubase 10.5 LE version however does not detect any MIDI IN activity.
Has anyone has some experience with this problem?

Have you checked in studio the settings to make sure the device is showing and enabled? To be honest this usually just works when connecting a midi device but worth a look.