I can't delete anything in TC. I opened a very large DWG file from an architect and tried to delete a lot of the non-relevant stuff. It worked at first, but then after a while would only work with repeated pressing of the ctrl+delete, and then not at all. I have done a restart, a virus check, and checked that the delete key works in another program (it does)
I must say that I find V20 to be somewhat dodgy- I am losing trust in the program and would go back to V16 if I could.