Editing a custom rule regex is broken

When trying to edit a regex in an existing custom rule, the content of the field disappears. I've recorded the behavior and put the video clip on this link:

https://tmtour.org/swaggerhub/edit_custom_rule_bug.mov 

Edit: This also seems to apply to the "Error message" input field.

BTW, if this isn't the correct forum for reporting bugs, please let me know and point me in the right direction.