Thanks for checking in, it was an unconventional recovery -
I was restoring a lightning node (on-chain and channel backups). My seed phrase was correct, but the lightning node software could not find the old UTXOs, despite doing multiple indexes/ restores.
So I thought, "no problem, I'll just throw the seed into sparrow and move the funds from there". But for some reason the seeds that Lightning Node generates are non BIP39 compliant (invalid checksum). Which I thought I could still choose to bypass in sparrow but didn't see that option any more.
I had to install "chantools" cli tool to plug my non BIP39 need into to generate a private key (xprv...), then use that to pull the wallet into sparrow. Recovered the funds and then moved them all to a new lightning node wallet 😅
The whole things took a couple of hours and multiple times I had assumed I was using an old seed and had lost the correct one.