It's interesting that as I went to the computer in question and logged in I saw your email. I had just restarted my other computer and was going to restart this computer. That did not solve the problem.
I did eventually find a solution. I'm not sure why this worked. I had File Sharing turned on and I had checked the box in the Get Info window for the drive for Share this Folder. This had worked for me prior to upgrading to MacOS 15.3. I turned off both and shut down the computer overnight. (I don't think overnight had anything to do with it but it was time to go to bed.)
In the morning I only turned on File Sharing since I only sign in with an administrator account. Walla!
Thank you for your response. It's always encouraging to know that someone cares enough to make suggestions.