Hi,
I have a multidimensional image service published from a mosaic dataset and also one published from CRF. When requesting a range of multiple times and changing the mosaic operator from mt_first to any of the others the same image is returned. I have tried this with a range of 30 time-steps and mt_sum looks exactly the same as mt_first.
example requests
https://xyzxyzxyzxyzxyz.com.au/arcgis/rest/services/dev_awra_historical/physical_day_mosaic_multivar...MT_SUM%22%7D&bbox=10522572.706631279%2C-7037490.874982109%2C18633458.652025748%2C819012.6402793587&imageSR=102100&bboxSR=102100&size=829%2C803
https://xyzxyzxyzxyz.com.au/arcgis/rest/services/dev_awra_historical/physical_day_mosaic_multivariab...MT_FIRST%22%7D&bbox=10522572.706631279%2C-7037490.874982109%2C18633458.652025748%2C819012.6402793587&imageSR=102100&bboxSR=102100&size=829%2C803
