WMS/WMTS on ArcGIS Online

Is anybody else having any issues with adding WMS/WMTS services to ArcGIS Online? I am able to add a WMS service and it appears in the content but no imagery is shown. I have no issue with adding these WMS/WMTS to QGis, ArcPro, or ArcGIS Portal running on Azure.

ArcGIS Online has (since about a year) an issue with WMS sources, that are not listed as under “specific domains”, see how to work around this:

We informed ESRI about it a while ago, but did not hear from them.

Thanks for the info Grega!