From forum: [https://forum.unity.com/threads/group-framing-mode-min-ortho-size-randomly-disappears-when-using-timeline.979665/#post-7127189]

It happens for me each time i change a script.
The Group Framing Mode comes back after i press play and stop once. (When in play mode the group framing is not working)
Unity 2020.3.0f1 & Cinemachine 2.6.4.

I created a new empty project but I was not able to reproduce the exact same issue I have.
The Group Framing Mode still disappears after a recompile, but when i press play it comes back immediately (as oppose to after i press stop in my original project)

Just change something in the TestScript to force a recompile and the Group Framing Mode should disappear.

Is is also possible to fix by resetting the follow target, or reselect Framing Transposer as the Body

Repro project attached