I have a similar problem to the one discussed in this closed thread.
http://duc.avid.com/showthread.php?t=375070
I have an academic copy of PT 10/11/12, but 12.2.1 is the newest version available to me for download from "My Products and Subscriptions" on my Avid account. Is there anyway to resolve this? I first discovered the problem when 12.4 came out. I was eventually able to get that but, if memory serves, that was via the Application Manager some days after the release.
I am hoping 12.5 fixes my lag problem – when I use my external monitor with pro tools running on my 2015 Macbook pro, the user interface becomes unusable. When I unplug the monitor everything is dandy.
Thanks!