The simulators have the ECU in the loop but of course most of the inputs are simulated and they come from models for car dynamics and all kinds of behavior that have a lot of correlations and assumptions built in. As in a flight sim, some of the models are empirical (more like curve-fitting than simulation of physics). Losing power in straights is something a team would be highly motivated to see predicted in the simulator as that’s within normal conditions. But it’s not surprising the simulator can’t predict some edge cases, you’d need to get a lot of things right in the modeling and think of weird inputs.

What they probably could do yesterday, on top of checking a ton of telemetry, is understand which inputs were weird and put those into a simulator and get some hints for the FIA to work with. If you’re not aware, the FIA provides the ECU to all teams so that the telemetry used to check compliances and power modes are fair across all teams, and things like traction control are not there. This is why the FIA had to provide the firmware update.