I have the same issue after updating to Version 71.0.3770.148, running on MacOS 10.14.6.
I have discovered that after clicking full-screen on the player that using Hide Bookmarks Bar, either from View menu or shift-cmd-B, takes the player to proper full screen. When using the player control or esc key to exit full screen, must Show Bookmarks Bar (again from View menu or shift-cmd-B) to get it back to normal. It works, but it's a hassle.