That is a bug in the update on some systems that was not found before the release. Adobe reports that they are working on it.
If you'd like to help us to test the After Effects CC 2015 (13.6.1) update---which fixes this bug---you can request access to the prerelease testing program here:
Choose the "Private programs" tab and click Apply to apply for the "After Effects CC 2015 (13.6.1) patch update" program.
The After Effects CC 2015 (13.6.1) bug-fix update is available. It fixes several bugs, including the one being discussed on this thread.
Let us know how things work after you have installed the update.
I already tested the update and it works.