Overlap actor check doesn’t pick up expected static mesh actor

Development Asset Creation
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We’ve found what seems to be a bug where very occasionally an overlap query isn’t returning an actor it clearly intersects. In a specific location, with a specific box size, calls to World->OverlapsMultiByChannel fails to find a large scaled floor actor, even though the actor overlaps the query box. We’re seeing this happen in UE5.6.1.

I’ve attached a minimal Blueprint only test project that recreates the failure by running the overlap test through Blueprint. When you enter play/simulate in editor, the Blueprint prints the name of the first overlapping actor in the query box around the ‘TargetPoint’ actor. This says “None” as no overlapping actors are being returned.

We found that changing the XZY position of the ‘TargetPoint’ actor as much as 2cm will successfully detect the floor actor. Similarly changing the floor actor’s scaling can also allow the same location to detect the floor correctly.

We spotted a similar bug back in May 2022 which appears to have been fixed. [Content removed]

This issue can cause our navigation graph generation to fail in ways that are difficult to distinguish from unrelated bugs.

Thanks

Michael

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Steps to Reproduce
Open the example and run PIE/SIE.

Level blueprint should run OverlapActors node, printing the name of the first actor or “None” if one isn’t found.

For reference, the the query box uses

Pos = (X=6400.0000000000000 Y=6400.0000000000000 Z=95.304687500000000)

Extent = (X=1360.00000, Y=1360.00000, Z=4643.93750)

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Hello [mention removed]​

Thank you for reaching out and bringing this issue to our attention.

Also, thanks for taking the time to craft a repro project; it helps a lot!

I was able to reproduce the behavior you described.

It’s interesting indeed - the behavior only occurs with the floor scale at (500, 500, 1); other values don’t reproduce it.

Moving TargetPoint also “fixes” it.

I’ll investigate some more and let you know.

All the best,

[mention removed]​

4

Hello [mention removed]​

I’ve confirmed the bug is still present on P4 main.

I’ve made a JIRA report at: Unreal Engine Issues and Bug Tracker (UE\-342357)

Please note that it can take some time to be made publicly accessible.

We don’t provide updates on EPS, but if you would like to track the resolution, check the link for the status.

I’ll close the case, but feel free to reply if you have anything else to add.

All the best,

[mention removed]​

5

Hi Rafael

Thank you for your response.

We are OK waiting for an official solution, this problem is not blocking.

Also, we have not found any other combinations of position/extent/scale which seem to reproduce the issue.

Best regards,

Michael

6

Hello [mention removed]

Are you blocked by this?

Let me know if you are OK waiting for an official solution or if you require further support.

I’m also curious if you found other position/extent/scale combinations that cause the overlap to fail, so we can look for a pattern.

All the best,

[mention removed]

7

Hello [mention removed]​

Thank you for your reply.

I haven’t closed the case yet as I was planning to investigate it further, but I never got the time.

As you mentioned, you are not blocked by it, so I’ll do it now.

Sorry for the delay between your reply and my closing it.

I hope it did not cause you any inconvenience.

All the best,

[mention removed]​