Plex not forwrding to Link suddenly

Echo Show, Echo Link, Group, Group speaker set to Echo Link, everything plays on the Link except Plex, which determinedly plays on the Show . Started around three days ago. Renders Link useless (I have no need to hear the weather forecast on a SOTA HiFi, and no wish to listen to music on a rubbish Amazon speaker).

Amazon say “Plex problem”, although they have raised a ticket.

Doubt it, but, any ideas?

No need for a new thread, Plex on Echo Flex not working.