> The first thing which is worth trying is:
> 1. Type M-x package-recompile RET auctex RET
> 2. Restart your emacs
>
> If it doesn't work, then try:
> a. Uninstall AUCTeX once.
> b. Restart your emacs and (before doing anything else) reinstall AUCTeX.

The problem was resolved after a new installation of AUCTeX, so not really
a bug. This issue can be closed (I think).

Yours,
Sandy