Unreal Engine Issues

Editor becomes unresponsive for long periods between edits of a user-defined enum type when it's referenced by one or more user-defined struct types.

After adding a member to a user-defined struct type and changing the member type to a user-defined enumeration, repeated edits to that enumeration will eventually cause the editor to become increasi ...

InstancedStaticMesh displaying corrupt lightmap data

I think I narrowed this issue down to bad UV coordinates being interpreted during the BasePassVertexShader execution applied to instancing. At this line in VertexFactoryGetInterpolantsVSToPS: flo ...

Sorting objects at EndLoad has a non-deterministic behavior

This non-deterministic behavior is caused by sorting by program address. ...

Crash in editor when loading a procedural mesh that has multiple sections and raytracing is enabled

[Submix][Content Browser] - Deleting an unsaved Submix asset (any type) causes them to reappear when creating a new asset

Deleting 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. ...

Crash on multi viewport when streaming in sub level with rect lights

Very thin meshes cause flickering with emissive materials.

The licensee has reported that when you make a mesh extremely thin (e.g. z = 0.0001), it can cause emissive materials applied to the mesh to flicker. ...

Crash when adding an Event Write node to a Niagara Scratch Pad module

It seems that the crash is related to all of the "Write" events. I tested the Event ChaosDestruction Write, Event Float Write, and Event Bool Write and all 3 caused the crash, but their "Read" count ...

Apex Destructible meshes are disappearing at certain distances during Runtime.

Green spheres at "4.3 - Destructible Assets" flash in an out of view. Can not be viewed on the left of the spheres.When playable play is close to the spheres they disappear no matter the position.Gre ...

Fast Path pin update can break when anim BP compilation generates warnings

It seems that a Anim BP that generates a warning will break the updating of pins that are connected via fastpath in other parts of the graph. This was reported on the following UDN: [Link Removed] ...