Hi Paul. First, thanks for trying to tackle my question solo last Wednesday.
IF you can find time, I’d love for you to view this link. There are fifty or so different versions of this same problem in insider hub, so the upvotes are affected due to the spread of topic names for this bug.
Prior to Creator’s, I could start a movie in Edge, hit Cast To Device and it showed all my DLNA appliances in the house. After Creators, it just searches. You can then do Find Other Devices and it shows them all, but you can not use them to cast to.
It was incredible useful to blast a movie to the XBox One or straight to the TV. Especially on websites that you really need AdBlock on to navigate safely. It’s very hard to work with the XBox One version of Edge on those sites, as the pop ups overtake the system.