'Hide Unconnected Pins' Button in the Blueprint Node Details Panel Disconnects SubPins with Connections

Development Programming & Scripting
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Hello, as the title suggests, the ‘Hide Unconnected Pins’ button in the Details panel of certain blueprint nodes can cause connected pins to be disconnected. Specifically, this seems to happen with any connected SubPin generated by the ‘Split Struct Pin’ pin operation (I used the ‘Break Neural Profile Struct’ node in my repro as an example). This repro is extremely easy so I don’t think it’s necessary to provide a repro project, but I can if needed.

I did a bit of debugging on the issue in FSkeletalControlNodeDetails::HideAllUnconnectedPins in SkeletalControlNodeDetails.cpp. The ArrayProperty used to track propertyhandles to struct members is not updated with SubPin properties generated from the ‘Split Struct Pin’ operation. When a Pin’s SubPin has a connection, it still satisfies LinkedTo.Num() <= 0, because it does not have any connections (it’s SubPins have the connection). As a result, FSkeletalControlNodeDetails::HideAllUnconnectedPins will hide the Pin with the connected SubPins and break those SubPin connections.

I’m reporting this bug in case it is unknown, and if there’s any fixes available, that would be great! Thanks for the help.

HideUnconnectedPinsBugSetup.png(433 KB)
HideUnconnectedPinsBugResult.jpg(336 KB)

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Steps to Reproduce

  1. Start vanilla Unreal Editor 5.7, and open or create any blueprint. I used the starting level blueprint for convenience.
  2. Add a new blueprint variable and set the Variable Type to a ‘Neural Profile Struct’.
  3. In the graph, add a Get node for the variable added in step 2.
  4. Connect the Get node to a new ‘Break Neural Profile Struct’ node.
  5. Expand the ‘Break Neural Profile Struct’ node, right click on the ‘Input Dimension’ output, and click ‘Split Struct Pin’.
  6. Connect the new output ‘Input Dimension X’ to a new ‘Add’ operator node.
  7. Select the ‘Break Neural Profile Struct’ node, and then click the ‘Hide Unconnected Pins’ button in the Details Panel.
  8. Observe the bug: The ‘Input Dimension X’ output is no longer visible or connected to the ‘Add’ operator node.
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Hi there,

Thank you for your report & especially for the detailed reproduction steps. I was able to confirm this in 5.7 and a few previous versions.

I have reported this as a bug. When it is reflected publicly you will be able to view it here

Cheers,

Louis

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Thank you for the response, bug report, and confirmation of this issue in 5.7! Any idea when the bug will be reflected publicly? It is still prompting me for a jira login.

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Apologies! I entered the wrong link. It should be updated with the correct on now

- Louis