I’m having an issue where I set all the keyframes to use Linear timing, but when I play back the animation the timing appears to flicker between Linear and Ease In/Out. This issue came up after I had been working on several versions of the animation, and I made this identical animation where linear timing was assigned successfully. When the timing flickers as shown in the video the animation appears choppy.
I’ve made multiple passes confirming that every keyframe is set to linear, creating the animation from a new element from scratch, and each time the result is the same.
I think all that you are seeing is the default easing selection which is normally set to Ease in Out.
The easing selector is set to show this so if you are not on/over a keyframe action it will show the default. When you are on/over a keyframe it will show what that is set to.
Hence it appears the easing is changing where in fact it is not.
As a further note, you can change the default for the document by control-clicking the timing function in the pop over window and choose Set as Default Timing Function.
I thought the animation itself looked like it was still easing, but maybe it was just slow down because I had so many keyframes in so little time.