Using Mac OS X 12.6.8 and Remote Desktop 10.9.2. Beginning two versions back (10.9.0?), copy and paste works for a while after launching RD, but it eventually fails when copying from the remote mach...
I've been dealing with this daily for over a year. I just found something in a post from 2022 that said it appears that the system is trying to send font information over with the copy/paste. If you change the font that SSMS (or whatever program you are copying in) is using to something that exists on your Mac, the problem should go away. You could also install the missing font on your Mac.
I've noticed that when the pinwheel comes up, if I go back to the source and copy it again, when the hang-up is over it actually pastes the data. If I don't copy it again, I get an error message.