I reported this issue on github a while back, but it turns out it is a reasonably serious DLL conflict. More details here:
Collaboration for Revit: 2015.6/2016.1 breaks other add-ins | Revit Products | Autodesk Knowledge Network
Users reported that installing the Collaboration for Revit® 2015.6 or 2016.1 add-in is causing other add-ins to stop working.
There seems to be a DLL conflict with the latest Collaboration for Revit add-in.
Status: This incident is currently being investigated for a possible cause and resolution
Incident ID: 72448
Workaround: Continue using the 2015.5 or 2016.0 version of the Collaboration for Revit Add-in.
Note: If you need to remove the newer add-in (Autodesk A360 Collaboration for Revit…), you will also want to remove the new version of the “Personal Accelerator for Revit” and “Dynamo 0.8.1”