macOS Catalina - problems detecting external monitors
How exactly are you connecting your monitors to your MacBook Pro, and what else do you have connected to it?

The MacBookPro's with 4 Thunderbolt 3/USB-C connectors actually have  2 Thunderbolt 3/USB-C buses, each connected to 2 ports, one pair on the left side of the computer and one pair on the right side. The specs that say the Mac can support 2 or 4 monitors do not mention this, but the fact is the Mac can only support half that number on each side. 2 * 0.5 = 1 so the spec is not lying, but sometimes you have to pay attention to which side of the Mac things are plugged into. 

Still, the Mac should support 2 DVI-resolution DisplayPort over USB-C monitors per bus, which makes me wonder exactly how you are connecting the monitors.

Try connecting one monitor on the right side of the computer and the other monitor on the left. Alternately, try connecting them both on the same side of the computer, connected directly to the computer and nothing else connected to that side.