I wasn't running any mods at first, but the last few times I tried I had a steam workshop scenario (DUWS) installed. I know it's not a problem that happens for everyone because I've watched videos on the internet and it was fine, it seems to only be a select few

I managed to get it to work by reloading my save starting at camp maxwell before tipping point. Also, I sprinted almost the entire way from the radio tower overlooking agia marina all the way to the boat