I have a 2013 991.1 cab with PDK and sport chrono. I drive in mountains and use the altimeter function, but recently it stopped showing altitude. The Nav seems to work fine, however.

Any thoughts on a solution? Is there some software flash that could restore it?

 

I'm not too familiar with the PCM3.1, but is it hidden behind an option somewhere? Are you viewing it on your home screen or your customized "cards" screen or whatever?

 

It is an optional line on the card of functions such as arrival time, oil pressure, etc.