I bet that happened because they are meant for alternating current, AC not DC. 20 amp Wagos CAN start to get soft at 60 amp AC if in a pull box. Wago makes a 30 amp larger version. I don't know if there is enough cool down the Wago gets wit the alternating current and wave form ramp up and ramp down, that allows more cooling. Where direct DC load stays at 100% load with no wave form cool down time even though the AC wave is ramping/ramping down 60 times a second. Here is a Wago test.