I posted on the Apple Community Forums. Maybe somebody there will have an idea.
A Google search provided some hits for various suggestions but I have no idea if they would work besides I don't even use Safari and I doubt if I would use pinned sites as it seems to have been a problem area for many for several years now.
However, try this guy:
5 Ways to Recover Your Safari Tabs After Restarting Your Mac
Do you keep losing all your tabs on Safari every time you restart your Mac? Here are some quick fixes to help solve that problem.www.makeuseof.com
Hopefully one of the suggestions works for you.
- Patrick
=======