Its not quite that simple, whilst the OBOGs systems are integrated with inflow, they dont go via the engines! Besides OBOGs has been around for ages and is fully understood against gen 3/4 jets. The critical issues are related to G onset rates and demand against the control laws at certain parameters within the gen 4/5 jets. In addition there are other issues within design which are potential show stoppers under a small number of flight parameters which until you generate a lot of flight hours do not appear in simulation. Thats about all I am allowed to discuss.
You dont think it has anything to do with the faulty ”Combat Edge” G-suit vest??