yep, had same issue as OP, except on Windows 10.
I'd have my set group, drag a window out, try to drag it back in and nothing would happen (command prompt or file explorer tabs, for example). Didn't matter how long the window was held over the group.
Luckily I still had my 1.19 installer, so I just reverted back to that from 1.21, so easy workaround for me.
icy`
