We had this, still not done with but what we did ...
Played show and tell at home
Dh and I both went in and read story to show that we overcame our nerves and he sat with us when we read. Only did it once each.
DS first issue was trusting teacher so we had big thing of teacher says blah blah blah made up report when it came to parents evening time. Said all kinds of stuff they didn't.
Following that had a big push on getting DS to interact with strangers in shops and adults we know and come across got him to pay for stuff etc and reminded him to say thank you.
Also then had big push about teacher. Got him to give her stuff he'd drawn or made or whatever. Just to get bond with teacher.
Had peers from class round slowly but surely. One to One bodning, even just once has been v useful for DS.
Now I know he's popular and has plenty of friends, is slow to trust other adults and that he liked Show and Tell until something happened and the class laughed. DS not impressed.
Think it's his personality but feel I've done all I can.
Oddly he's happy standing up in assembly and all other things, it's jus a show and tell thing. Dont blame him it's dull as hell.