I'm experiencing this odd bug with Houdini Engine and Unreal, if anyone has any ideas. I'm stumped, it seems to happen as soon as I add an object to the World Outliner Object Merge. I tried adding an Output node, it didn't help. I also remade the HDA to be just this problem, replicated exactly.

Am I doing something wrong?

Hi,

You're not doing anything wrong, that issue is actually caused by a regression in the plugin.
I was able to reproduce and fix the issue, the fix will be in tomorrow's daily build of the plugin.