Hello [mention removed],
Thanks again for the report. I’ve now submitted this issue internally to the engine team. Once it becomes public, you’ll be able to track its status here: Unreal Engine Issues and Bug Tracker (UE\-358149)
Regarding the cause, this is an infinite loop in the editor. In UE 5.3 and later, assigning a Sprite Atlas Group to a PaperSprite causes UPaperSprite::PostEditChangeProperty to be triggered twice. The first call corresponds to the user-driven change, while the second call occurs during atlas rebuild propagation and comes through with a generic property change event. During this second call, the sprite attempts to rebuild the atlas again, which re-triggers the same code path. This repeats indefinitely, resulting in an editor hang and eventual crash.
As a temporary workaround, the loop can be prevented by guarding the atlas rebuild logic in UPaperSprite::PostEditChangeProperty so that it is skipped when the change type is EPropertyChangeType::Unspecified, similar to how rebuilds are already skipped for interactive changes. For example:
if (PropertyChangedEvent.ChangeType != EPropertyChangeType::Interactive &&
PropertyChangedEvent.ChangeType != EPropertyChangeType::Unspecified)
{
// Existing logic for atlas rebuild
}
This should avoid the infinite loop and let you set the Atlas Group property. This workaround was taken from the following forum post:
https://forums.unrealengine.com/t/paper2d-sprite-atlas-group-issue-in-5-3-2/1772474/9
Please let me know if you need anything else on this. Otherwise, I’ll go ahead and close the case.
Best,
Francisco
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