I like this post not only for the useful information, but also for the fact that you found and quoted everyone who mentioned the same issue!A few months ago, my delivery location changed (by itself) from Bluewater to Staines. Also at some point, my EDD disappeared from the app (like all of you). I don't know if they happened at the same time because I didn't realise the Bluewater->Staines change for a while. I went on live chat today and asked them to change it back to Bluewater. And now my app is once again showing my EDD. May be coincidence but thought worth mentioning!
I'm almost scared to change my location just in case I get bumped in a queue somewhere on Tesla's mythical/legendary EDD system.