Just finished upgrading our Enterprise system to 10.6.1, and I am now able to create hosted feature services with survey123 (yay!). Unfortunately, all the feature services on my portal are unable to open in ArcMap 10.6.1. Either from portal selecting the 'Open in ArcGIS Desktop' option from the feature service page (the file downloads, but nothing is added to arcMap) or if I log-in to my portal from inside arcMap, view the list of feature services and select 'Add' in the lower right corner. Nothing happens. No error messages. Nothing. It may be unrelated, but on portal, if I go to settings for the feature service and try to set 'Enable editing' I get this error.