We don't know what went wrong with the investigations but they've been screwed with somehow. This is what we think happened but no one knows for sure until afc reveals all his hidden powers and roles.
Day 1 investigations were correct when Valley got a NON TOWN read on Tobes & its meant to be 100% correct, and was proved true. At the same time it seems via Neville's posts about the tags & ACS liking his comment that ACS investigated Funky on day 1 and got a TOWN read, and that was correct too. Acs had a 25% chance of investigating but it should be 100% accurate as far as we know.
Day 2 something happened, we don't know what but a few people think it might have been a secret mafia power. Suddenly investigations got switched around and seemed to return incorrect results. Valley investigated Mito and got a NON TOWN result, this was meant to be 100% accurate and yet mito was TOWN, so we know that was 100% the incorrect investigation result somehow.
On the same day mito investigated me and got a NON TOWN result, as drunk PI his investigations are 67% accurate according to the OP (he didnt investigate night 1). Both these guys revealed themselves and we spent the next 2 days debating the results. I thought I had just been unlucky due to the 33% incorrect result coming up on me, as I'm a no role townie. As valley was correct on Tobes there was a lot of confusion as most players had town reads on both mito and myself, eventually a bunch of people realised that the investigations might well be wrong so they switched their votes away from the two of us.
Unfortunately mito was killed by the meth head, he was asking to be killed to prove his innocence and to have his weekend free... After he died and was shown to be town people realised the investigations were stuffed. There was always an element of doubt about me being non town due to the 33% chance of incorrect result, and after realising that investigations could not be trusted more people believed i was town, mostly due to the way i had been posting throughout the game & voted.