Same issue here. Mac Pro (late 2013), 3.5GHZ 6-Core Intel Xeon E5, 16GB DDR3, AMD FirePro D300 2GB, MacOs 10.15.2 Resolved by dropping graphics down to low, then manually upping a few things to medium. Sometimes when they start saying 'it is a hardware issue,' it means they have started dropping support for older graphics cards.