Need a hand,Mask type error

CW1173 ChipWhisperer-Lite.When I use fixed mask type,it’s work well.But an error has occured after I use random mask type.‘decimal’ codec can’t encode character u’\uff0d’ in position 1: invalid decimal Unicode string.
It is usually safe to continue, but save your work just in case.If it persists, try reseting the settings first before creating a new ticket informing the details bellow.
How to solve it?

Hi, can you provide more details? Which version of CW are you using? What script, notebook, or GUI settings lead to this error?