In case someone else hits this problem:
I had a problem recording and playing back audio in Cubase AI 9, using a Surface Book (i7/16Gb) and a Steinberg UR242 audio interface.
Recording sessions were extremely frustrating because of constant audio drop outs that happened randomly. Cubase would stop recording as to avoid gaps in the recorded audio. I also experienced random gaps during playback in Cubase with or without the audio interface. Position of the gap changed every time I played the song.
Apparently I was able to overcome the problem by disabling AISO-Guard in Devices->Device Setup->VST Audio System, at least so far it seem to have helped, as I was able to work on a 5-minute piece without drop-outs where before I was never able to do it without drop-outs.
According to this article, AISO-Guard was supposed to minimize audio drop-outs, but I guess in my case it was causing them.