OK, here are the pressure values you are sending...
press: "1,017.1"
pressH: "1,036.0"
pressL: "994.8"
pressTH: "1,017.1"
pressTL: "1,008.1"
presstrendval: "0.7"
pressunit: "hPa"
The gauge code attempts to parse the supplied values by first scanning for commas and converting them to full stops (to allow for the many people around the world that use comma for a decimal). This is the first time I have seen data being sent with commas for thousands separators. The gauge code is interpreting your values as pressure = 1.017 etc.
I don't know WC, but can you change the number format to stop using a thousand separator? It is unusual to see one in pressure values anyway.