I’m fairly new with this game and have for the most part been enjoying all that I’ve been encountering so far but unless I’m missing something here I cannot continue with this mission. I’m in the room where I’m directed to search the house for more info about the cairn but the diary on the table won’t let me touch it. There’s nothing here for me to collect to continue the mission.
I never found it either. It’s not on the board in the kitchen or something? Someone will have found it. It just irritated me on the hud all the time. However, I had a look at the map and figured out where “The Path of the Gods” must be and went and collected the stuff anyway! I found chummy’s camp as well - I fear he didn’t make it!
My mission completed when I got there, in spite of the fact that I never found the “clue”. Tip: it’s at the end of a path that doesn’t go anywhere else.
P.S. don’t follow the path - walk in the woods above it and when you get there, I thought the cairn was defendable, but it isn’t - you get shot from below…
was able to pick up the journal for the clue on an attempted playthrough before but one of the updates broke this mission. even knowing where the clue is supposed to lead me and going there doesn’t complete it for me. there are many bug reports like this one The Path of the Gods unplayable so hopefully they know about it
Thanks for the replies, helps to know I’m not alone with this one 
I couldnt pick up the journal either but did collect the loot at the end of the path
did picking up the loot complete the mission for you?
No, its still splashed across my screen as an incomplete mission.
Likewise, I found at Orsnabben lookout point a stash that was related to the mission but the diary thing is still on the table and the mission on my screen 
Welcome to the forums. This is a well-known issue that has been reported many, many times on all platforms, and has been acknowledged by the devs. As such I’ll add the ‘acknowledged’ tag to this topic. In the future, please use the search function for any issues you might have instead of creating a new topic. Thanks.