Unfortunately that’s not BTC… it’s “BTC” Omni asset number 97, which I expect could never be redeemed for BTC.
On this page, it states only Omni assets can be traded on Omni Dex:
It would be great if it could also have worked with actual BTC, or if Tether on Omni was still easy to buy / sell, but unfortunately I don’t think it is, so Omni DEX is as good as dead.