We were not able to reproduce it but would like to help you with it. May I ask you to open a support case with all the logs attached and let us know your case ID? And yes, we do offer best-effort support for customers using free versions.
Hello Joachim,
Couldn't confirm the issue as well, but I guess the thing is that "Guest disk space" is a Parent/Child alarm.
Sometimes one child alarm is resolved while another is in error/warning state. That may lead to situation like yours. I'm not 100% sure, so please contact the support team as Fedor suggested above.
Thanks!