Percona APT repo being ignored (maybe OT)

We just had a massive failure of one of our DB cluster nodes, and noticed during the forensics that we were running XtraDB Cluster version
and not the latest version (5.6.26-75). When I went to update apt to get the upgrade to -75 I noticed the percona repo is being ignored for some reason. I’m not a n00b to linux or Ubuntu, but this one has me stumped.

Are the repos up? Or am I missing something simple?

Can you show us the error or how you are trying to update/upgrade?

According to the download page, these are the existing versions:
5.6.27-76.0 <–latest

Eh, I screwed up, I was looking at the standalone MySQL server versions and comparing that to the XtraDB Cluster versions, which ARE different. It was a long week just before the holidays and my brain stopped working. Apologies.