Image Occlusion Enhanced for Anki 21 alpha

When trying to use the Image Occlusion Enhanced add on a message comes up telling me to restart anki when holding down shift - I did this and now all my image occlusion cards appear as a little white square (as shown in the image). The restart message appeared again saying it is the fault of this add on. I was wondering how to fix this as otherwise hundreds of my cards are now invalid and I don’t have time to remake them!!Screenshot 2021-10-17 at 23.02.27