Hello Kalle,
I have a MIDI controller keyboard and have tried it, the computer keyboard and the piano roll the same thing occurs.
All VSTs work except for drums and they worked until the day I reported the problem. When I go to record the drums I can hear the drums when I play my midi keyboard but no signal (midi or audio) is recorded. Past recordings with those same drums play through properly.
However, drums in VST packs that are part of a number of instruments such as BBC Symphony Orchestra, DSK Indian Dreamz and Cakewalk TTS1 have no problem only dedicated drums such as SI Drum Kit, DPinga Congos and Bongos, H-1 drums etc. exhibit this issue.
I read the posts and tried the solutions but none worked.
Rebooting and reinstalling those drum VSTs does not work and neither does installing new drum VSTs that were never previously installed.
I will keep troubleshooting for a few days and failing any solution will try reinstalling Cakewalk even though its the last thing I want to do.