Create Frame no longer works the way it used to. It needs to inherit the Background template. Went through and changed all of the Frames that were throwing errors from :SetBackdrop. Example of what was changed:
before: i = CreateFrame("Frame", "", a);
after: i = CreateFrame("Frame", "", a, BackdropTemplateMixin and "BackdropTemplate");
Create Frame no longer works the way it used to. It needs to inherit the Background template. Went through and changed all of the Frames that were throwing errors from :SetBackdrop. Example of what was changed:
before: i = CreateFrame("Frame", "", a); after: i = CreateFrame("Frame", "", a, BackdropTemplateMixin and "BackdropTemplate");
After doing this, the addon seems to work again.