Can you take the membranes out of the cartridge? see if you can get flow with empty cartridges, then make sure the membranes are in correctly.
???
2017 - 20ish taps on buckets, boiling outside in two baking pans
2018 - 70+ taps, 14-buckets, 50+ on tubing, homemade arch from oil tank in my barn, 17 gal syrup
2019 - same set up, 20 gal syrup
2020 - less taps, short season, but RO kit was fantastic! 6 gal syrup and a maple cat!
2021/22/23 - expanded into the neighbors yards! 50 taps on buckets and 40 taps on tubing