The Landscape warning, looks it like it needs updating, but I don’t see if it does anything else with them.
At the end its a connection time out, but the last thing it says before that timeout is waiting for camera’s
Are you using any camera’s ?
In the video the landscape does look like its not loaded properly, maybe since your already in fortnite the landscape validation issue is causing it to timeout ?
Do you have a yellow triangle in your editor viewport ?
Close fortnite and select all your landscape tiles and right click Save selected actors
Rebuild HLODs and then relaunch session