Unpredictable nDisplay + Switchboard node startup behavior in UE5.6

Hi everyone,

I’m running into an issue with an nDisplay setup in Unreal Engine 5.6 and was hoping someone might have run into something similar.

I’m working on a custom project using nDisplay with Switchboard, and when I try to launch multiple nodes, the behavior is inconsistent:

  • Sometimes all nodes start correctly

  • Other times, one or more nodes freeze during startup and show a black window

When the nodes get stuck, only some of them show the following as last log line:

[0] LogDisplayClusterEngine: Display: CheckGameStartBarrier - we are no longer out of sync. Restoring Play.

A few additional observations:

  • The more nodes I attempt to launch simultaneously, the less likely they are to start successfully

  • This happens both when Switchboard’s “Launch As” parameter is set to Standalone or Packaged Game

  • It also doesn’t seem to matter whether I use a local installation of Switchboard or a remote one

  • Sync Policy does not affect the outcome (currently set to None)

So far, I haven’t been able to identify a clear pattern or bottleneck.

Has anyone experienced similar synchronization/startup issues with nDisplay in 5.6? Any ideas on where to start debugging this would be greatly appreciated.

Thanks in advance!