Field Testing DC/DC Solar Charger

I have a kings dcdc 25amp charger this has built in solar regulator and quick play Anderson plugs I’ve set up and used in multiple scenarios but recently duplicated for my boat and the spare charger for my boat
Solar panel quick connect and I have been applying same process with vehicle and leaving it not plugged into starter and just charging a camp fridge via the solar and battery box
Now what blows my mind is when I use the voltage meter on the solar Anderson plug terminal I get my 20+ volt and corresponding when plugged in the solar light flashed green
Assuming providing power to the unit
Now I have then test the plug for “battery output” or even the plug for alternating input but I don’t get a reading (assumingly close to 14v is what I’d expect but I get no signs of power- only when I wire up as per specif direction unless I have it wired perfectly I on sometimes see a full load current from the battery reading 14v
The battery box tends to just stay around 12.7 v it’s like it’s not working 🤦