This should really be a sticky somewhere from SESI, but folks - when you're posting a problem it saves a lot of time if you briefly mention the configuration you're running. It can be as simple as:
Houdini 6.1.208, Linux RH 9
and of course if you're having display problems it's worth mentioning the card you're using and the driver versions.
It saves a lot of time because very often there are known bugs that were fixed in later versions…
Thanks crew…
J.C.