A lot extra Achievement

I have had every objective, bonus, and optional done within weeks of the game release. Never got the achievement. progress is at 94% still. this has been stuck for years nows. please fix

update: I deleted local saves and have them synced back when I started the game back up. not sure if this helped at all or not but anything was worth a try. I then went back and did the entire campaign ( original 12 missions) on easy with skulls that made it extremely easy and just focused on doing every bonus mission again. I eventually got the achievement after it was stuck at 94% for years even though it the missions said I completed it. I got the achievement on the second to last mission. my recommendation is just going back through the campaign. no saves just start to finish on each mission and just focus on getting each bonus done on each mission until you get it.