I have a config with 3 labels as below.

I then add a value for a 4th label to the same config

I then delete the top value for label 'eu-dev', after deletion the name of the labels is wrong

I then refresh using the refresh button in the portal and the labels names correct themselves.

Thank you for reporting the bug. The fix is in progress.
The fix is already checked in, it is planned to be deployed to all regions in about 2 weeks.