Sorry for the trouble, I confirmed the bug can be reproduced with your attached project file. However, if I create a new animation in the project, I can grab the shear handles with no problem. It seems there are some specific conditions, but we have not found it yet, so we would appreciate it if you could wait a while until we complete our investigation.
I have created an issue for this bug as I seem to have found the condition:
https://github.com/EsotericSoftware/spine-editor/issues/637
Apparently, the bug only occurs when the bone is constrained by a transform constraint. It occurred even though the interface scale was set to 100%. We are sorry for the inconvenience, but we would appreciate it if you could wait until the bug fixing is completed.
We've fixed this issue in 4.0.62 and it has been released. Please update and check if it is solved.
