Stops rendering with a peak

Cubase 9. Was rendering audio through outboard compressor, with asio guard on medium setting. Tried about 6 times and each time it just stopped in the middle, after generating a new track, but without the rendered audio.
I think there was a big cpu peak at the moment when it stopped rendering. Worked fine after disabling asio guard.

Rme ufx on 48khz 24 bit, windows 10, nothing in background