Help me. No milk flow with medela symphony is it the flange size?

My baby is on a nursing strike and I can't pump despite having a hospital grade pump and no problems using the same pump in the hospital even renting another one so I have two symphonies to see if the pump was the issue and it wasn't.

There's no milk flow/

I eventually have a thirty second let down of 10 ml and then that's it for the entire session unless I stop for twenty minutes and pump again and get another 10 ml let down.

I tried going to a 21 mm but I can't tell if it fits.. help please.

The info graphics are just confusing to me.

21

24 below and this is with pump off.