As a newby I just thought i would share my experience with a corrupt preferences file.
For some reason the dimensions of my shape layers were showing up all sorts of weird measurements. A perfectly square rectangle, sized to fit composition (1000px x 1000px) was showing up as 1000px x 738px.
Completely confusing. Read somewhere that corrupted preference file can cause all sorts of strange things to happen.
If you are totally confused about something and AE is acting plain weird, try dumping your preferences, it worked perfectly. Experienced users would be used to this, but beginners not so.
Clearly, the foundations of AE 2019 are creaking under the weight of new code added to old code and these things happen.
Just thought it might help some people who are scratching their heads with it!