Workflow automation trigger - cannot select when "Any field" changes

When creating a brand new workflow, we can specify it to trigger from changes in "Any Field", such as below:

However, I would like to modify some of my existing workflows to have them trigger when "any field" changes (as shown above) but that option is no longer available in the dropdown. I am only able to choose one of my existing fields. It seems that the "Any Field" choice is no longer available on existing workflows.

Can anyone suggest a workaround so I don't have to recreate my numerous workflows? Perhaps having it trigger off the Modified (system column) to simulate a change in any field? I imagine that would have the same result, but I cant be certain.

Thanks in advance for your feedback.