VERIFIED SOLUTION i
When a layer with MRR raster image is turned on for a map configuration and any area is clicked upon to open call-out, message 'SERVICE_ERROR Internal Server Error' is observed. If 'DevTools' window is kept open, following message is observed on the console tab:
It is a known defect in Spectrum Spatial Analyst in version 12.2 and earlier. Call out is not expected for MRR raster layer.
ResolutionUPDATED: November 6, 2018
This has been fixed in Analyst 2018.2. Upgrading to this or later version of Spectrum Spatial Analyst will resolve the problem.