Possible Grease Pencil Bug: Clamping Underlying Pixels failing

Reference: https://www.youtube.com/watch?v=qPrp4wFjQnQ
Timestamp of event: 5:46
Build: https://i.imgur.com/wlJoZ6P.png

Whenever I attempt to clamp underlying pixels, sometimes it works, sometimes it fails. However, as seen very late in the video, it stops working altogether! Am I the only one experiencing this problem? Am I doing something incorrectly, did they fix this in a later build…? I have no idea about what I am supposed to do in order to fix this or otherwise prevent it from happening.

May I please ask if anyone is capable of confirming I am not going insane here?