I’m just encountering this now as well. Its killing my workflow. I read on the Adobe forums that if I copy and paste it to another Ai comp it will work, but it doesn’t seem to solve the issue for me.
I really hope they address this soon though, it’s ridiculous. If you try and save legacy or older, it even pops up a disclaimer that it will be read 10x smaller. Looks like any way I save it, its 10x smaller though.