Hi Jan,
I used several interfaces (USB-USB, USB-MIDI) on several keyboards (Roland 700NX, Yamaha P155). The problem is not specifically intermittent, but depends on the note sequence you play. With some note sequences the problem can be reproduced every time.
Please note that I don’t talk about the known pitch wheel overdub issue.
At this moment Steinberg is investigating the problem and will post here when they have a solution or other information.