I updated recently a DataMiner to 10.3 CU10 version. As I could check on the documentation, this is the minimum version to have available the custom operator on Dashboards without enable a soft-launch option. However, I cannot see a custom operator in my query, but it is installed through the catalog:
Why can't I apply a custom operator?
Have you tried to follow this example ?
If it still doesen't work let us know, maybe you are missing on some step or definition on the Automation Scripts