I have used LR since Beta 1 for windows & have not had this problem.
I go thru a folder in Library mode & use x to reject images. When I am finished I go to Photo & select Delete Rejected Images & press mouse & they are not deleted. I get "There were no rejectes to delete".
Same results if I use Ctrl+Backspace.
LR Classic 9.4, Win 10 Pro 64 bit, version 2004 build 19041.572.
Seems to be a "bug", is anyone else having this problem or has a solution?
When I finished & returned to working in LRC I was told upgrade was available. I just upgraded to V 10 but still have same problem that I cannot delete rejected images except using Control key & clicking each image. LR & Win 10 both up to date.