thanks for your post, and sorry for the trouble.
That’s something that I’m still looking into. Indeed, TablePress adds its own right-click context menu to cells. It’s however not intended that no context menu is shown while a cell is already being edited.
I hope to be able to find the cause for this soon, so that either the native context menu or the TablePress context menu can be shown in that case.
In the meantime, for copy/paste, I can only suggest to use the keyboard shortcuts Ctrl/Cmd + C and Ctrl/Cmd + V.
Thanks for the update! I hope it can return one day but understand the complications.