Unreal Engine Issues
Unreal Engine Issues
BoxOverlapActors fails to catch an Overlaped actor with a particular scale, from a particular position
UE - Simulation - Core - Sep 30, 2025BoxOverlapActors fails to overlap a scaled Floor actor with a particular scale, from a particular position and extent. The setup is really specific and described in Steps to Reproduce. The required ...
Wrong density calculation in UBodySetup::CalculateMass
UE - Simulation - Core - Sep 29, 2025Wrong density calculation in UBodySetup::CalculateMass. The licensee has provided the following analysis and suggested fix: In UBodySetup::CalculateMass, the following code is present: // physical ...
Soft angular constraints solve velocity like hard constraints
UE - Simulation - Core - Jul 17, 2025Soft angular constraints are solving velocity like hard constraints. Instead of swinging back and forth, the affected body just snaps to 45 degrees. Check the steps to reproduce for more details. Th ...
Non-Nanite Instanced Static Mesh Collision not showing in collision view
UE - Simulation - Core - Apr 3, 2025This issue is the same as [Link Removed], but it causes confusion for developers because only Nanite ISM are rendered correctly since UE5. . ...
Mirror operation on Physics Asset produces wrong results for constraints, including flipped axes
UE - Simulation - Core - Feb 7, 2025The Physics Asset Editor has a "mirror" feature that allows physics bodies and constraints to be mirrored from one side of a skeleton to the other. If this operation worked correctly, it could save ...
A Skeletal Mesh simulating physics that hits a Geometry Collection Actor with OneWayInteraction true, OneWayInteractionLevel 1, and is using Damage Propagation (default) will be accelerated so fast it immediately disappears by hitting the world limits
UE - Simulation - Core - Jan 20, 2025A Skeletal Mesh simulating physics that hits a Geometry Collection Actor with OneWayInteraction true, OneWayInteractionLevel 1, and is using Damage Propagation (default) will be accelerated so fast ...
Physical Material Mask bug found in GetPhysMatIndex, potentially causing issues with lookup.
UE - Simulation - Core - Dec 2, 2024On line 408 of UPhysicalMaterialMask::GetPhysMatIndex() in PhysicalMaterialMask.cpp, the AdjustCoord() function is given AddressX for both the U and V coordinates. The AddressY input is never used i ...
Calling BodyInstance.UpdateBodyScale displays erratic behaviors and does not update the rendering scale
UE - Simulation - Core - Nov 22, 2024Calling BodyInstance.UpdateBodyScale displays erratic behaviors and does not update the rendering scale. The licensee has reported and presented a repro project that displays the erratic behavior of ...
UAT crashing at end of build calling FScopedSceneLock_Chaos::LockScene()
UE - Simulation - Core - Nov 7, 2024UAT has intermittent crashes at the end of packaging. Looks related to [Link Removed] . Could be that the solver is being destructed after the null check earlier in the function if this is multit ...
Changing the Global Time Dilation to a very small value and returning it to a large value (by either using the slomo console command or directly in BP) makes Physics simulating ragdolls fly off into space.
UE - Simulation - Core - Sep 26, 2024Changing the Global Time Dilation to a very small value and returning it to a large value (by either using the slomo console command or directly in BP - slomo sets TimeDilation) makes Physics simula ...