Interruption in Cutting

How do I turn off this interruption in cutting?

Peculiar but we would need to see the LBRN file to confirm

Make sure you have no AutoMatic Tabs enabled

Any chance you can upload your LBRN file?

just draw a square with the tools on the left
I turned off all Tabs and the problem disappears in most colors,but it remains with the black color

That, I believe, is because the color black is configured with “tabs”.
Access the black color properties (as you did in the others) and deactivate the “Tabs”