Hmmmm. First off - seriously appreciate ya playing and letting me know! Second - have you tried interacting with the letter and pressing “f”? It should pick it up. Either way, I’ll upload a fix that automatically picks up the letter when ya have the key.
Hey! Not sure if you get notified about the other replies - but the issue was totally on my end. A collision box that overstayed its welcome. Uploading the fix now - apologies! Should be up in like 30 mins (slow internet is slow). I have no idea how to do patches so unfortunately, you'll have to snag the whole game again. When the file name is CaptainMidnight_1_16.zip, it should be good to go!