ID 144679 - Creation of Backdrop node doesn't trigger onUserCreate callbacks

Problem summary
Using addOnUserCreate callbacks with Backdrop nodes does not work.

Customer reported version
Nuke 11.3v4

Customer reported platform
Windows10

Steps to reproduce

1) Run the following code in the Script Editor:

def backdropTest():
    node = nuke.thisNode()
    nuke.tprint(node.Class())
    if node.Class() == "BackdropNode":
        print 'Backdrop'
    else:
        print 'else'

nuke.addOnUserCreate(backdropTest)

2) Create a BackdropNode in the Node Graph and notice that nothing is printed out in either the Script Editor or terminal.

3) Create any other type of node (ie. Grade) and notice that 'else' is printed in the Script Editor and the node class is printed to terminal.

Expected behaviour
addOnUserCreate callbacksshould work with BackdropNodes the same way they do with other nodes.

Actual behaviour
Using addOnUserCreate callbacks with Backdrop nodes does not work.

Workaround
Using an addOnCreate callback instead will work as expected.

Reproduced by support

This bug has been reproduced in:
Nuke 11.3v5 - Windows 10 - Linux CentOS 7 - macOS 10.13 (High Sierra)

Nuke 11.3v1 - Windows 10

Nuke 11.2v1 - Windows 10

Nuke 11.1v1 - Windows 10

Nuke 11.0v1 - Windows 10

Nuke 10.5v1 - Windows 10

Nuke 10.0v1 - Windows 10

Nuke 9.0v1 - Windows 10

Nuke 8.0v1 - Windows 10 - Linux CentOS 6 - macOS 10.13 (High Sierra)

Earliest version tested
Nuke 8.0v1
- This issue appears to be in all versions of the product