The more a mixing console is used, the more problems you may have getting label tape to stick.
The big culprit here (unless you spilled a beer on your mixer) is skin oil. This invisible contaminant builds up a little every time you touch the desk, and is even more of a problem if you are sweating.
The oils in your hands and in your sweat reject the adhesive on the tape, causing it to curl and slip on a surface that may appear clean to the eye.
A quick rub with a hand wipe is ususally enough to solve the problem.
Larger buildups may require using a lint free cloth with a little mild soap. Alcohol will work as well.
Whatever you use, make sure you completely dry it off.