At some point, Nunchuk stopped supporting static XPUBs. If you change your SeedSigner to the Sparrow export setting, it will animate the QR code that depicts the XPUB and the rest should work fine. I ran into this a couple of weeks ago as well.
Unable to get nostr:npub1cvqlzvmjercdn0ypsmv8f7j9lge6ahsnueh5rparh53wuswftv4q49yjt3 mobile wallet to scan an Xpub from my nostr:npub17tyke9lkgxd98ruyeul6wt3pj3s9uxzgp9hxu5tsenjmweue6sqq4y3mgl. Tried using both Testnet and Mainnet with no success. Tried my Mainnet Xpub on Blue Wallet and that worked fine.
Discussion
Bingo, that did it. Thanks!
Where else can you get quick answers like this? nostr:npub17tyke9lkgxd98ruyeul6wt3pj3s9uxzgp9hxu5tsenjmweue6sqq4y3mgl
and Nostr rock!
nostr:note1yl0wqsrhqqm85434vhjjgrgkd2uvj72l03mt0lt409lw9zlf54eq36tgdm
Interesting. Might be a regression bug. Do you have a sample (singlesig) static QR for an XPUB? We can take a look and debug it.
For sure, thanks for checking into it -- give this one a try: 