Hello,
Lets get right into it. I completed Rct Training, and aside from the basic acre stuff it went relatively well.
After joining a server with a few other 15th members we kit up, mount up, and push off, half way up a river in the map "Prei Khmaoch Luong" we beach our boat and decide to continue on foot.
As soon as I hit V to dismount I lost every asset on the map. Grass, Trees, the boat, the marines, and myself. Assuming this was an easy fix, I re-spawned and noticed the entire base was gone as well.
It's noteworthy to mention that I was able to locate the invisible arsenal box, and grab a mortar from the launchers, thank you weapons squad. I deployed the mortar, and mounted up, which allowed me to see the assets, people, buildings, and trees alike.
I also tried the below actions all to no avail:
googled the issue (many people think it's an issue with cup terrains, but no one mentions a fix)
deleted cup / reinstalled
switched from vanilla launcher to Arma3Sync / re-attempted downloads
cleared 'appdata' cache of mp misisons
assets work in SP and editor / only affected by MP servers (Santos' personal server and the below image from the SOI training server - on Altis)
problem persists on vanilla maps, but seems to be linked to multiplayer settings.