[brianogilvie]

You cannot place a single action on hold. The On Hold setting in the Inspector applies to the project, not the action (which is why it's in the Project Inspector, not the Action Inspector).

One solution some people have done is to create an On Hold context and set its status to On Hold. You can then place actions on hold by putting them in that context.

I don't have a need to place single actions on hold, so I haven't done this myself.