Need urgent assistance!

Alright so here's a long story short. I have a lot of games on my gamertag that I no longer own due to borrowing/renting the games before I buy them and the ones I am not interested in I just leave them be.

I thought one day, why don't I just mod the achievements since the games are just sitting there doing nothing. So I ended up modding a few games + arcade games that I no longer own and I'm having a slight issue with the modded achievements.

For the games that I've completely unlocked it is missing a single achievement out of the whole list yet when I go to my achievement list it says they are all unlocked. Not to mention my gamerscore went down a little seeing that it registered as 1 missing out of all of them. It's quite strange.

The programs I used were Horizon and Profile Editor. I made sure I rehashed and resigned my profile before I put it back on my xbox and everything was fine until 1 achievement off each fully modded game is not registering. Is there something I did wrong? I simply just unlocked all achievements offline seeing I didn't really care about adding the times to it and it wasn't that many games (only 4).

I'm not much for modding to be honest - I just got bored and wanted to try that out. Is there any way to fix this issue? It's really bugging me for some reason.

Thanks in advance,
-Drol