Signature Field keeps disappearing from webform

I love this module when it works.
I included this field into a webform.
It works great when you set it up, but then, the next day it disappears.
The funny thing is that in the form there is still space reserved for the signature field, only the field is not there. (the title of the field is not visible either.

Performance / Clear all Caches - seems to be fixing the problem temporarily, until the next day when it disappears again.

Please help.