assert/crash on compiling abt when using linked animgraph

Steps to Reproduce

Repro steps:

  • Empty 5.5.4 project with a skeletal mesh and a skeleton

  • Create a BP deriving from Actor (BP_CrashRepro)

    • Add a Skeletal Mesh Component using the available skeletal mesh
  • Create an empty Animation blueprint template (ABT_Link)

    • Add an input pose to the anim graph, connected to the output.
  • Create another Animation blueprint template (ABT_Base)

  • Add a linked anim graph node connected to the output.

    • Set its Instance Class property to ABT_Link
    • Connect an Input Pose node to the Linked anim graph.
  • In BP_CrashRepro, set the skeletal mesh component’s anim instance to ABT_Base

  • Crash/breakpoint triggers only when:

    • BP_CrashRepro AND ABT_Base are open,
    • The user compiles BP_CrashRepro first and then ABT_Base (which will now assert/crash).

Using the attached project, you only need to follow the last main bulletpoint for the issue to occur.