Hello! Hope you’re doing OK and that the machine has started to behave again?
If not, usually the biggest culprit on Sage machines when froth/foam isn’t able to be produced from the steam wand is the holes being blocked on the end. You’d be surprised how often this happens!
You can check if this is the case by using the end of a paperclip to poke into the holes on the external end of the steamwand, in case they have been blocked by solidifed milk.
Also, unscrew the end of the steam wand tip (when the machine is switched off and has cooled down over the course of an hour!) to check if the inner steam wand has been blocked as well.
Sage/Breville do sell cleaning tablets that dissolve milk solids and effectively clean the steam wand but you do need to manually clean first as the chemical cannot dissolve all of it!
Once you’ve used the chemical as a solution, you can also check that the steamwand is clear by putting it in a jug of cold water and steaming it until hot, no chemical. This should eject anything clogging the holes that has come loose.
Finally if the steam wand is spick and span and it’s still not working you can then check:
The steam pressure in your tank - this will be affected by a buildup of scale (always filter your water)
The quality of your milk - skimmed and low-fat milk will not steam as well as other types!
Hope that helps!