It looks to me that inserting a Time Sig marker changes the timeline annotation - the annotation is shown at the position of the time sig change and continues in increments from there.
As in this example:
I think that it would be clearer if the timeline annotation were always displayed in regular units of 4 bars and multiples and subdivisions (32 bars, 16, 8, 4, 2 bars, 1 bar (N beats), N/2, N/4, N/8 beats etc) depending on the zoom level.
So in that screenshot the timelins would be annotated at bars 1, 9, 17, 25, 33, 41 etc. And on zooming in a bit, at bars 1, 5, 9, 13, 17, 21, 25, 29, 33, 37, 41 etc
This may need to be an option. And configurable?