I have been working on a project in ArcGIS 10.5 and found out today (after sending the data) that the main two people that are going to make use of my work are only using ArcGIS 10.3.1 (most of the organisation has already updated to 10.5).
I do not have access to 10.3.1 (I am remote contractor) and while the users can update to 10.5, they can't do it at short notice and yet they need to test and use the data and tools I have sent.
I have used Save a Copy to back-wards save the MXD from 10.5 to 10.3, and they can now successfully open the MXD, but the one ArcToolbox tool they needed in the toolbox I sent was not visible (yet visible and usable in my ArcMap from the same folder).
I figured maybe the toolbox had also re-saved as 10.5, so I did a Save a Copy on the toolbox, back to 10.1/10.2 (the next version back in the selector) - but now they can only see one tool total in the toolbox!
Previously they could see 10 of 11 tools.
How can I make all the tools visible/available in ArcGIS 10.3 if I only have access to ArcGIS 10.5?
Another angle may be that it's not a version issue but rather something else that may be preventing their ArcMap from seeing the script tool.