Missing Layer Pick Lists In Geoprocessing Tool Dialogs
Summary
ArcGIS 10.x has a bad interaction of the Item Description editor with geoprocessing tool dialogs, related to a common (but not default) ActiveX security setting. This issue is common, but does not affect all users because not everyone has the same ActiveX security policies. The problem has been observed in ArcMap and ArcCatalog (ArcGIS 10.4 and later).
To check for the issue:
- In ArcMap: make sure you have at least one feature layer in the map
- Open the Buffer tool (Geoprocessing > Buffer) and verify if map layer(s) appear in the drop down for the first parameter. You should see all feature layers in the active data frame available in the dropdown.
- Right click the layer in the TOC, choose Data > View Item Description
- Click the Edit button to open the editor, then Save, then Exit.
- Open the Clip tool (Geoprocessing > Clip) and verify if map layer(s) appear in the drop down for the first parameter. If drop down pick list of layers does not work (that is, the tool dialog is not "seeing" map layers or table views) you have this problem.
Workarounds
Fix #1
If in ArcMap, save your ArcMap document. Close and re-open the application. This is not ideal as you need to interrupt your ArcGIS desktop session.
Fix #2
If you work in an enterprise environment that only allows admins to modify these settings, or changes them back to a standard setting by Windows Group Policy, this fix may not work. You should consult with your computer management staff about these changes.
- In Windows 10 search box search for: Internet Options
- The Internet Options Control Panel should appear. Select it to open the dialog.
- Go to the Security tab, select Local intranet, Custom level..
- In the Security Settings dialog scroll down to: ActiveX controls and plug-ins, Allow previously unused ActiveX controls >Enable
I got very excited when I saw this document as I have been suffering this problem for years. I followed your instructions but my ActiveX settings are already what you suggest setting them too. So whilst for some users this may solve it for them there seems to be others (i.e. me) where the problem lies elsewhere. Would be good to resolve this. My more immediate problem is that a windows 10 update has broken the links to the help file, so clicking on help on any geoprocessing tool takes you to a blank page, but that's another issue.. 
I had this problem as well but then noticed it was appearing in the top right corner of my second monitor. Any idea on how to solve this?
