When using signature field, I was suprised to see that it only seems to be loading the canvas and making it drawable, if it is on the first load.
Meaning that if I have a signature field at the last form page, it is not editable.
This is because it doesn't have "width" in it's styles attributes. and not in the width attribute either.
Setting
canvas.jet-form-builder-signature__canvas { width: 100%; }
in my custom CSS fixes this issue.
I have tried to switch from % to px in the blok setitngs as well - made no difference.