Hey @dlksabm,
Unfortunately no direct solution or feature to enable more detailed logs. I scoured the project, even our plugins for any array that may have been modified while being iterated over. There was simply nothing. In the end we concluded it must be something deep in the engine that only occurs while cooking (PIE and Simulation play modes always worked).
We did find an issue with similar logs denoting nested child actors (that is child actors within child actors) were to blame and that will be fixed in 5.4. I’ve been able to build with nested child actors before so to me it’s doubtful.
As a last ditch effort we started eliminating potential candidates, that is recent blueprints or settings in our levels which could have led to such an issue. First and foremost we disabled One File Per Actor (OFPA). We’d had some issues with it in the past and were always sceptical of it’s efficacy. Then we went about “debriding” maps. At first we deleted everything in entire maps to narrow down the offender, then rolling back the deleted objects piecemeal till we found the one or two assets that were causing the issue. Funny enough we simply deleted them and readded the same blueprints to fix it.
I have a suspicion that the issue snuck in while we upgraded to version 5.4.3, or when we introduced OFPA, or some version control shenanigans. Some of our team are fairly new to Perforce and or UE and so may have not been adding every external actor or something.
My suggestion would be to try the same approach we did. Triage the situation by clearing maps and doing builds till you get a successful one and then restoring some levels and objects to hone in on the asset(s) causing it. Also ensure your whole team is on the same UE version and has committed all their work to your repo.