Swarm Lighting Build Fails in Source Build. "Failed to cache the required dependancy" HELP!

I’ve been trying to build lighting in a source build of UE 5.1 but I keep getting “Lighting Build Failed” after starting the Swarm Connection. I’ve rebuilt UnrealLightmass and followed all the solutions listed at the bottom here:

The error in Swarm is:

23:51:36: [Job] Accepted Job E9BD80D0-4CF00661-8D49658B-E97BA0AB
23:51:37: [Interface:CacheAllFiles] Failed to cache the required dependency: S:\ps5ue5\UnrealEngine-release\Engine\Binaries\Win64\embree.dll
23:51:37: [Job] AddTask: Rejected, cannot add a task to a running job
23:51:37: [CloseConnection] Closing connection 4546072C using handle 4546072C
23:51:37: [CloseConnection] Connection confirmed for disconnection 4546072C
23:51:37: [CloseConnection] Closing orphaned Job (E9BD80D0-4CF00661-8D49658B-E97BA0AB)
23:51:37: [CloseConnection] Connection disconnected 4546072C

Any ideas what this might mean and what the solution is?

Cheers, Lionel

Edit: I’ve also tried building the lighting in a seperate project using the same Unreal Source build and it fails the same