The high side current shunt monitor fault goes high as soon as power is turned on preventing the P-MOSFET from turning on, its not faulting because of over current but as soon as the Enable signal goes high the Fault also goes high with it. the 3.3V is the first signal that comes on after the 18V.
Figure 1. Problems with logic levels?
I haven't looked at the INA200 datasheet at this stage but it seems to me that you have a few potential issues.
Q1's emitter is pulled up to 3.3 V at (3) and (4)but the very most its base can reach is 2.5 V at (2) even if (1) is running on 5 V logic.
Is this intended design?