January 2019
I am now having this very same issue.
I've have never had any mod's or custom content. It started after I purchased the new expansion.
I cannot rotate my view on my camera at all.
Repairing game didn't resolve the issue.
Any suggestions?
May 2019
I've repaired my game twice and it's not working for me. Broke after the latest update.
December 2019
I've noticed this for the last four months ago - off and on. I just fired it up today after 2 months and the Sims 3 camera mode middle mouse button tilt camera does not appear to work AT ALL
You can hold down CTRL and the RIGHT mouse button to do the same thing - although this seems to use the opposite orientation, so you will also need to change the horizontal and vertical rotation settings.