A. This can happen normally if the user is on ignore. (has ignored last edit)
B. This can happen if all the user's edits were deleted. (shows no last edit)
C. This can happen if the user creates a page that is still in the moderation queue. (has hidden last edit) Since rebuilding user edits did not work, I would check this, since the edits must be in the database.
Fixed both B & C for 3.0.17 since A is desired behavior. Only new edits/deletes will be counted correctly. Already wrong counts will still be wrong.