Yoroi: Byron 21 word paper wallet? Confused


I generated an offline wallet through Yoroi by opening the firefox extension, turning off the wifi, and then generating the wallet. I’m new, so I learned that only a Byron paper wallet is possible at the moment. The process yielded a 21-word seed, which is unusual to me all together since the mobile app will ask for a 15- or 24-word seed.

I was able to restore this to another online computer successfully via Yoroi firefox as well. However, I can’t seem to restore this 21-word seed to my Yoroi mobile app…

Any suggestions? Or is this just the limitations of a paper wallet at the moment?