This was an issue for me in Houdini 18.0 as well, but I thought this was due to Solaris being so new. Unfortunately, this still happens in 18.5.
Pretty much every time I select a light or camera I get this Popup, usually several each time:
As this has to do with Python 2.7 I am wondering if I can force Houdini to use Python 3?
Or does anybody else have this issue?