I had the same issue, it's with the something in the carousel scaling option. I usually have mine on small and had the same problem, changed to normal with the same problem, unchecked the scaling option completely and problem solved.
Went in and turned on my MOE and colored tank highlights and it came back. I'm still investiagting a bit
UPDATES:
2 row smaller size works fine, so it's something with the colored tank highlights or the MOE and other info on the icons
2 row smaller size with mastery marks and MOE works fine, so it has to be with the colored highlights of selected tanks, so turn that off and you should be good :)
