Have you installed the Unreal plugin when installing H17.0.459?
Yes. I also tried reinstalling 17.0.459 but got the same messages.
However, today I upgraded to 506 and the problem went away. Perhaps I didn't check the “Houdini Engine for Unreal” checkbox like I remembered, but I'm almost certain I did. I guess me being at fault is the most likely explanation though.
drichardson I guess me being at fault is the most likely explanation though.
Turns out I'm not crazy. The issue appears to be related to how UE4's build tool decides when to recompile it's Rules assembly (which contains the Houdini build.cs file). @dpernuit is aware of this issue but until it's fixed, you can workaround it by deleting the UE4Rules.dll in the UE4 engine folder (thus forcing it to rebuild).