Unreal Engine Issues
Unreal Engine Issues
UClass::SparseClassDataStruct null at editor-time for child blueprints until compile
UE - Framework - Blueprint - May 29, 2024Child blueprints of a blueprint of a native actor class with sparse data can have an incorrectly null SparseClassDataStruct value, and thus fail to initialzie their SparseClassData. This affects edi ...
Bug: Level Sequence OriginOverrideLocation not propagating to newly added nested ShotTracks
UE - Anim - Sequencer - May 14, 2025Within a Level Sequence, it's possible to override the transform (OriginOverrideLocation) of a ShotTrack. This generally works as expected — all nested ShotTracks should inherit and apply the transf ...
Chaos Trailing Events not exposed to Blueprints and only accessible via Niagara Chaos DI
UE - Simulation - Visual - Apr 22, 2025Chaos Trailing Events not exposed to Blueprints and only accessible via Niagara Chaos DI. The licensee noticed that the Trailing event is not available to BPs. It's expected that the same data avail ...
Delta struct serialized fast arrays replicating new elements with no changelist
UE - Networking - Jun 14, 2021There is a scenario where delta struct serialized fast arrays can replicate changes that introduce additional elements to the array, but without changelists containing the new data. This needs furt ...
When used with First Loop Start Frame Offset and Use Animation Blueprint, the character will alternate between the specified animation and the reference pose
UE - Anim - Anim in Engine - Jan 30, 2023If you use StartFrameOffset set to 1 or higher in conjunction with the Use Animation Blueprint, the character's animation will be rough towards the end of the section. Specifically, it seems that th ...
Crash when calling FillDataTableFromCSVString() while viewing the contents of the data table
When the function UDataTableFunctionLibrary::FillDataTableFromCSVString() is used from Editor Utility Blueprints or Python Scripts, and the contents of the affected Data Table are currently being vi ...
IKRetargeting Skeletal Mesh Does Not Update Virtual Bones
UE - Anim - Rigging - Retargeting - May 20, 2022Occurs 5/5 times. Regression does not occur: UE5Manny Skeletons are new to UE5.0 ...
WorldPartitionConvertCommandlet hits an assert when converting a persistent level that contains a sub-level with a landscape
UE - World Creation - Worldbuilding Tools - Nov 7, 2025Context: The Window tab allows a user to open the Levels window in order to add a sub-level to a persistent level. For Unreal Engine 5.0 and beyond, World Partition has made the Levels window obsole ...
UNetDriver server-side hitch results in ActorInfo->NextUpdateTime far into future
UE - Networking - Feb 16, 2024A high UWorld::Tick DeltaSeconds (i.e. GameThread hitch) results in a high UNetDriver::TickFlush DeltaSeconds. This DeltaSeconds can high (many seconds) if the hitch is long. This value then affects ...
Niagara - When Interpolated Spawning is disabled, the first frame of each particle unexpectedly does not take into account the Particle Update stage
UE - Niagara - Feb 28, 2025Foreword: Even if the behavior described here is by design, it is rarely (if ever) expected or desired. This was discussed and agreed to be treated as a bug. Explanation below. When interpolated sp ...