Ahh you're right! My mistake about Kyyyte. Leave it with me and hopefully I'll have an update for you all soon.
Could you try one more thing if that's okay/possible?
I know it's difficult with the FPS issues but would you be able to try and leave the MUTINY ISLAND REGION?
You can leave the region a few ways but the simplest is either stealing a raft in the ocean or crafting one using Wood, Cotton and Sturdy Rope. There's also a stationary raft which you can use SOUTH-WEST of MUTINY ISLAND. Jumping off a Temporary Raft will make them sink so keep that in mind. Grab the RAFT pictured below and leave the map edges to be taken to another area. If possible, try and head EAST or SOUTH. WEST will more than likely get you killed as it's the more dangerous route.
In the meantime ANYONE who encounters this issue please continue to post your details in this thread.