I think I can see the issue visually, one of my spawned characters is hanging in mid-air for some reason.
I had a crash as well but now I know it was unrelated to this character movement issue, now the game is stable but the warning is still there.
This is the code I’m using to spawn my player characters in game mode’s BeginPlay. It’s a hot-seat local multiplayer game, basically a clone of HoMaM 3. 
I’m spawning four characters and getting the error three times. I’m possessing my all new characters by controller 0 and then again the one that should actually be controlled by the first player. I have a feeling there’s something I’m not doing right there.
LogCharacterMovement: Warning: GetSimulationTimeStep() - Max iterations 8 hit while remaining time 0.091142 > MaxSimulationTimeStep (0.050) for 'Hero_C_2147482465', movement 'Walking'
LogCharacterMovement: Warning: GetSimulationTimeStep() - Max iterations 8 hit while remaining time 0.091142 > MaxSimulationTimeStep (0.050) for 'Hero_C_2147482438', movement 'Walking'
LogCharacterMovement: Warning: GetSimulationTimeStep() - Max iterations 8 hit while remaining time 0.090483 > MaxSimulationTimeStep (0.050) for 'Hero_C_2147482432', movement 'Walking'