I'm having a problem with the display of an image layer in ArcGIS Online. The layer is a reference to a REST service of a DEM (image mosaic) from our state's GIS office. I have it set to display with a stretch symbology, min/max, and an elevation color ramp. It is also set to dynamically adjust the range. Sometimes it works just fine, but more often the color ramp has a strange stepped characteristic (note the display of the color ramp in the attached screenshot - it should be as shown in the second attachment (ElevationColorRamp)) and the ramp is also reversed - the white is the lowest elevation while the blue is the highest.
Another issue is that it often stops displaying at all - particularly as I've been trying to troubleshoot.
Does anyone even have any ideas about what is causing this?