I have the following layout:
In my case, it looks as if the issue is with build LRX22G:
Nexus 7 using Build LRX22G (android-5.0.2_r1) - progress bar not shown
Nexus 5 using Build LRX22C (android-5.0.1_r1) - progress bar shown
See https://source.android.com/source/build-numbers.html
It's probably also related with https://code.google.com/p/android/issues/detail?id=77865
Not being able to wait for a fix, what I've decided to do is to force the Holo progress bar to be used in my Material theme. This is how it was achieved - it may be of some use to you in the meantime: