[PopUp Pro] Color choozer issue

Hi there,
I can't choose a hex number for a color in the Popup Pro manage area. See screenshot, that's all I'm seeing.
https://www.dropbox.com/s/5sfvzoy3jhkusnn/Schermafdruk%202018-08-25%2012.10.24.png?dl=0
How can this be solved?