Try Write Tag (Auto) instead of Write Tag (Raw)
Thanks for the quick reply & brain power @masterchan777. That options seems to be disabled for me in both the original APK as well as your build. I'm unsure what the red warnings (top left) mean, or if they have any impact.
For what it's worth I'm also having problems with NFC-Bank bins -- nearly every one I attempt to open (like 8-bit Link, for example) complains about the signature.
Screenshots attached.