I don't think it would be the "file corruption bug"... as that would have required that you had (at least attempted to create) multiple wallets/seeds... and you seem very adamant that you did not have multiple seeds/wallets etc.
So, either you did have multiple wallets setup... in which case that makes things like using the wrong wallet possible, in addition to the "file corruption bug"... or you didn't have multiple wallets setup... in which case the file corruption bug is not possible.
The curious thing is that you're sure you had previously used the seed to restore the wallet (at least once)... and that you could see the transaction etc... but the wallet was always "offline"?
That isn't possible... if you had restored the wallet, it would have had to have been online at some point to be able to see the transaction... All wallets are created empty, and need to be online to retrieve the transaction data.
Or am I misunderstanding and you're saying you restored the wallet once (prior to updating etc) and it showed the "lost" address, but not the transaction data?
So, either you did have multiple wallets setup... in which case that makes things like using the wrong wallet possible, in addition to the "file corruption bug"... or you didn't have multiple wallets setup... in which case the file corruption bug is not possible.
The curious thing is that you're sure you had previously used the seed to restore the wallet (at least once)... and that you could see the transaction etc... but the wallet was always "offline"?
That isn't possible... if you had restored the wallet, it would have had to have been online at some point to be able to see the transaction... All wallets are created empty, and need to be online to retrieve the transaction data.
Or am I misunderstanding and you're saying you restored the wallet once (prior to updating etc) and it showed the "lost" address, but not the transaction data?