Auto Build hangs up

Just happened again, Docker Hub’s Auto Build hangs up~
But this time it’s a bit different from the previous two. It only in the tag which be repository linked in build, and the other tags will end normally.

Guess the program that might be reproducible:
Image A has A1, A2 two tags
Image B has B1, B2 two tags are FROM A: A1

1 - Image B setting to turn on Repository Link
2 - Image A is triggered by Push Code Auto Build A1 and A2
3 - Wait for Image A and Image B to complete all tags
4 - Close Image B’s Repository Link settings for a short period of time after completion
5 - Immediately after changing the settings, Let Image A be triggered by Push Code to Auto Build A1 and A2
6 - At this time, A2 can be completed normally, but A1 may hang there.