Unreal Engine Issues
Unreal Engine Issues
RF_WasLoaded is set to False in PIE for instances of a Blueprint if the Blueprint is recompiled
UE - Gameplay - Blueprint - Apr 5, 2019The RF_WasLoaded flag is set to false for Blueprint instances in PIE if the Blueprint is edited and compiled. This is fixed by saving the level which is a simple workaround but this should be needed ...
Cannot change Collision Profile of BP component instances
UE - Simulation - Physics - Oct 24, 2019BP instances placed in level cannot have their components' collision profiles modified to anything other than default and custom. Note that this did not occur in 4.22 (after applying the separate ...
Niagara system loses source emitters when moving Engine from 4.22 or earlier to 4.23 or later.
UE - Niagara - Nov 29, 2019The following code causes this behavior.// NiagaraSystem.cpp for (FNiagaraEmitterHandle& EmitterHandle : EmitterHandles) { EmitterHandle.ConditionalPostLoad(NiagaraVer); if (!EmitterHandl ...
Problems in skeletal mesh merge
UE - Editor - Content Pipeline - Asset Build - May 10, 2021There are a few issues a licensee has found with the skeletal mesh merge operation. See the UDN for more details and the proposed fixes. Note, the issue with the cloth merge is already logged in a ...
[Submix][Content Browser] - Deleting an unsaved Submix asset (any type) causes them to reappear when creating a new asset
UE - Audio - Submixes - May 13, 2021Deleting unsaved Submix assets causes them to reappear the next time you create a new asset. Issue does not occur in 4.26, but does occur in 4.27 and 5.0. ...
UMaterialBillboardComponent does not render when moving
UE - Graphics Features - May 19, 2022Marking this as a Regression since it works as intended in Release 4.27.2 (CL-18319896). I've also confirmed the behavior is occurring in UE5 Main (CL-20283975) as well. ...
bIgnoreAllPressedKeysUntilRelease only applies to keys in the previous mapping
UE - Gameplay - Input - Jun 16, 2022This is because the RebuildControlMappings function only checks this flag when you have a mapping that was already added, we should apply this for any new mappings as well. I'll update the repro s ...
Physics Constraint returns incorrect values for Swing1, Swing2, and Twist
UE - Simulation - Physics - Jul 7, 2022Tested in //UE5/Main CL#20966071 Tested in //UE4/Release-4.27 CL#18319896 Physics Constraint returns incorrect values for Swing1, Swing2, and Twist. ...
Disabling bLerpUVs in Nanite Settings of Static Mesh causes texture warping in clusters
UE - Graphics Features - Nanite - Jan 21, 2025The licensee has identified a potential fix by changing if( Settings.bLerpUVs ) to if( Settings.bLerpUVs || UVIndex == 0 ) On line 389 of NaniteBuilder\Private\Cluster.cpp in UE 5.5 ...
Copy-pasting custom property nodes (ControRig etc.) results in invalid bindings, perf issues
UE - Anim - Rigging - Control Rig - Jul 28, 2025From this UDN: [Link Removed] Suggested fix:Override PostPasteNode to perform the GUID update andAdd validation on load to strip 'invalid' copies that do not correspond to a valid pin input ...