Timeline unit won't toggle - only frames are displayed

Hello everybody!

Today I have encountered a strange error behaviour regarding my timeline in Premiere Pro CC18.

For some reason I was not able to toggle between frames, seconds and feet+frames. After some research I found that this might be due to framerate settings. Is it right, that for framerates higher than 60fps there is no option to display time and feet+frames?

Best regards and many thanks for your answers!

Sönke