I recently insisted my BMW dealership check for EGR Cooler failure after coolant loss with no apparent escape! Pressure test was ok; technician diagnosed egr Cooler failure & the dealership are raising a claim case with BMW even though my build doesn't currently appear on the UK BMW EGR Cooler recall technical campaign! More info here
https://www.bmwblog.com/2018/10/23/b...lion-vehicles/
My build is a 2014 F31 320D N47 efficientDynamics auto
My advice; if you're coolant goes low for no apparent reason; take it to a dealership & demand a test regardless of whether your build is on a recall list or not, & fight your corner before anything catastrophic & costly occurs!