No sure if anyone here had the similar issue.
I had number sharing enabled on my apple watch for almost 3 months, works perfectly well. Few days ago my watch screen come off suddenly and I have get it replaced from Apple. but now when I paired my phone it says my plan is no longer eligible for apple watch. I have tried calling and online chat, one of the rep disabled my number sharing profile or something but still doesn't work. Very frustrated as seems no one in Optus how to resolve this issue. I might just ask them to cancel my plan as the whole point I take the post-paid plan is to have number sharing feature.
had faced a similar issue, but i couldn't use back the backup on new apple watch for number share. Had to redo linking all from scratch[zero data on apple] and number share seemed to work after that.