Just a thought but when she is connecting via RD she is using an enhanced session right? In my experience if it isn't an enhanced session then the clipboard service doesn't work.
Copy and Paste Not Working on a Remote Desktop
I have a client who cannot copy and paste across her remote desktop session. I'm able to do so fine on mine. Both connections are set up exactly the same (so Clipboard is ticked on both, drives ticked, etc.). It also works fine one other people's connections. It's just this one person having the issue.
The connection is to a RDS server ( a VM on a Hyper-V - both Windows Server 2016). My client's laptop is Windows 10 Pro, all up-to-date in updates, drivers, etc. Mine is a Windows 11 Pro and others are using W10 Pro as well.
The client is a little "picky" and can't understand why she can't do this when others can.... I've created a shortcut on her remote desktop to her laptop desktop so she can drag and drop instead but (a) she doesn't like this and (b) the link keeps breaking credential-wise every week or two and I have to recreate it! I've done some research without a successful answer but I just don't have time to spend hours and hours continuing to do so.
So hopefully someone can point me in a good direction.