Star Rating Not Working.

I am currently trying to go through a wedding and star my photos off of a Seagate external hard drive. I have two separate ones and neither is letting me star. I try command and the number and it won't stay. I also try clicking on the star and it won't stay. It immediately disappears. I have a macbook pro, which it does work on. But I started using my iMac and it won't work on there.

I just updated everything on the iMac because I haven't used it in a while.

Thank you in advance!

Jill