Okay, I have a couple things for you to try. I don’t have an xSIID, but I do have an NExT v2(not a final version). Same chip, but I think it’s set up slightly differently compared to how the xSIID comes from DT. See if you can use NFC Tools to format it.
If that doesn’t work, you can try writing to each page following these instructions. I was able to write to each page individually with Advanced Commands in NFC Tools, or all at once with RawNFC from DT.