Is the glass that it's against still see-through? If so, it may not look/feel secure to him.
I've also known some that just don't care for those half-logs. You might consider getting a dark plastic bowl or small pot, cutting a small hole in it, and turning it upside down. Or if you like the naturalistic look - more of a cave dwelling than a half log.
One of our BPs really prefers this over a half log:
![]()