Those are bold statements to be made. I asked freitas10 to attach a save in my thread so I have a chance to check. But instead you go on spreading your theorie about the mod being at fault. I do not call that fair.
Edit: For you, I re-played the whole thing, solving the altar puzzle to get the map of the treasure chest (without having the key yet), going to that island (still without key), digging out that chest, entered the right combination so that I would be supposed to use the key (which I not had), left the chest. Then I solved the whole Erik route up to the poit that his father would give the stolen goods to me, where I found the key. Went back to the island, entered combination, used key, opened chest (which of course still was locked because I was not able to open it without the key before), found compass, took it.
No problem whatsoever, even with newest mod installed.
So, unless you attach a save here I cannot reproduce your issue, especially the claim that the mod has anything to do with it. Which I doubt very much because it does not change anything along those quest lines, especially not between the most current and any earlier version of the mod.