I can get back the Paste Special Dialogue by menu command or Ctrl-Shift-v. It just remembers and pastes the last option (which I made in error).

EDIT:
I "kind off" solved it.

I had copied an E-mail and accidentally pasted as hyperlink. I deleted the item and tried Ctrl-Shift-v. However, the dialogue didn't open, and the hyperlink was just pasted again. The solution was to recopy the the E-mail and thereafter do the Ctrl-Shift-v. I then got the dialogue.

Why is it necessary to recopy the E-mail when it is already in the clipboard?

BTW, I am often experiencing something similar when pasting hyperlinks. Not sure if related; After pasting hyperlink there are often several line breaks before and after the link. The "solution" is to delete it and recopy/past the link. It then pastes fine.