Drawing substitution keyframe bug

Hi, I’m having a problem with my lipsync drawing substitution keyframes deleting.

It doesn’t always happen but sometimes when you add or change a drawing subtitution keyframe, nearby keyframes change to that drawing.
It happens both when changing via the library slider and using the shortcut keys and can effect a few or lots or keyframes near the playhead.

One way of stopping this bug is to click on the frame in the timeline before changing the drawing but this is very tedious.

This image shows before and after with keyframes deleted on the bottom.

If anyone has experienced this before and has a solution, that would be great.