Seems unlikely that the logger would choose to only mess up humidity, I don’t believe we have ever seen that before with the Davis.
Hopefully Brian has some ideas?
If you want to investigate some more it’s pretty easy to do a basic setup for the VP in WD. I would temporarily install a second instance of WD using the 2wd.txt method so it doesn’t affect your main WD. Let it run for a while with just a minimal VP setup and see if you get the same result. That will tell you for certain if the Davis has a problem.
So long as you run that for less than 40 hours you will be able to restart the original WD and catch up the missed data.