I have been trying to make custom SF symbols, but I keep getting the error that the provided variants are not interpolatable, and even when I command-Z back to where, when I tested, it was interpolatable it says it still isn't, the file is somehow corrupted and I have to delete it. I don't know what could be wrong, this happens even when I try to make my symbol from template files. Both are interpolatable symbols but when I combine them for some reason they aren't anymore. I can't figure it out. Everything is in the same layer order, etc.
For example, when I take the circle and rectangle templates and simply copy and paste them into one Illustrator document and then move each circle out of its layer into the layers Ultralight-S, Regular-S, and Black-S, it works. But when I do the same with my own custom symbols, even exporting their templates from the SF symbols app, it doesn't work and says "the provided variants are not interpolatable". I seriously don't know what to do. Even if I take one of my files that imports fine and move one of the symbols over slightly it won't import anymore, saying it's not interpolatable, and when I use undo to go to where it was before it still won't work and says it's not interpolatable.