That reddit user was NOT saying that there is definitely a bug that caused that... they were just saying that it *might* be a bug.

My honest opinion is that it is not a bug and most likely the result of some confusion on your behalf... whether this is just because it has been so long since you set it up that you don't remember 100% what happened between when you originally set up the ledger and wrote those words down... and now when you are trying to restore your ledger.

You say that you did transactions successfully prior to trying to do the update... but that doesn't require you to input the seed. You just need to unlock the device with the PIN. PINs are not related seeds... they're just a security option for the device, so you can use any PIN with any seed.

So, it is possible that at some point you had reinitialised the device with a new seed after you wrote the words on the card you have... you'd still be able to do transactions, but the addresses you'd be using would be completely different and unrelated to the seed on your card.

Not having first hand knowledge of exactly what you have and have not done makes it difficult for anyone other than yourself to truly know what has happened in this instance.