Loading vector tile services in the ArcGIS Online Map Viewer shows Out of Memory error or hangs, when created from Point features that have no fill and no outline, and the symbology was set in a MXD that was imported into ArcGIS Pro.
Reset the no fill and no outline symbology in ArcGIS Pro after the MXD has been imported. Issue only occurs when the symbology has been set in and carried over from ArcMap.