I find it unlikely foggy would be able to edit the investigation, unless his role was explicitly to receive and share paranoid/insane investigations (could be a useful role, but I feel it would become rather obvious somewhat quickly given that he has publicly outed himself as the one giving the investigations) Therefore, I think the best assumption is to think either Notty or HK is lying (the report received by Arelic was also received by Foggy and thus we know Arelic cannot be lying, but the report shows nothing to Arelic's alignment). However, I'd like to point out that this situation basically has the signature of a bus driver. Consider this: Hk visits a mafia at night who had swapped themselves with notty, Notty tracks HK who is swapped to visiting Notty, so Hk thinks they visited someone else, but Notty sees HK visiting her, similarly Foggy/Arelic's investigations to notty get swapped and whatever Mafia Hk had tried to visit was the person they received the report for.
I'm very much doubtful Foggy would claim if his role gave fake investigations, so I trust he is telling the truth.
It doesn't matter much what Arelic's alignment is in this situation, so that's largely irrelevant right now.
Notty suggested HK might be the one to come forward. If notty is a desperate mafia this seems like an unlikely move to try to throw foggy and Hk as a team when there was no previous evidence of it (If anyone finds a reason that move would make sense please let me know)
It's possible HK is a framer and actually visited Notty, but is lying about it now for obvious reasons. If we assume he is lying that would pretty heavily point to him being mafia/third party anyway, so there isn't much point in exploring the possibility that he is lying and not a framer right now.
then there is the third possibility I mentioned above involving the bus driver. this makes a lot of sense to me because it explains everything and isn't as unlikely as a bus driver. There are 16 players in the game and a bus driver would visit 2 of them, so changing investigation results would become 1/8 instead of the 1/16, so I think this is more likely, but Ideally I wish we could see evidence of this first.
HKCaper You claimed not to have visited notty last night, but you never said who you did visit. It seems to me like this might be important.