I am trying to run an Optimized Hot Spot Analysis in ArcMap version 10.5.1. This tool worked for me a couple of weeks ago but now there is an error icon next to the Input Features (screen shot attached) and no matter what input layer I select (projected/unprojected/shapefile/feature class etc.) the error does not go away. It doesn't provide details about what the error is when you hover or click the icon.
If I ignore the error and set the tool up to run as usual it gives the below error message with no details.
Am I missing something obvious? Is version 10.5.1 no longer supporting this tool or something? Is it time for me to upgrade?
Any help would be appreciated.