I'm afraid dirt from the CO2 tank has stuck inside the regulator's 1st stage.
Please follow steps to fix this issue:
- remove the regulator from the cylinder
- release all gas from the regulator so both gauges are on 0.
- remove the CO2Art logo sticker from the back of the regulator
- unscrew the bolt from the back with a large screwdriver
- please\, clean internal side of the regulator and make sure that there is no dirt on the bolt side
- assemble all back together and test it.