Unique tool grayed out

[Newt]

A workflow has a Unique tool immediately following an Input Data tool.   The Unique tool checks one field, which is present in the Input Data flow.

Upon re-opening this workflow, the Unique tool is grayed out.  It still seems to be working, separating out dupe records.  What can cause it to go gray?

[atcodedog05]

Hi @Newt 

Is it running successfully when you try to run it ?

[zrob]

Likely it is behind, and not inside, the tool container you are using