It's not a bug, the house/car EQ presets are completely independent. Why would you want to use an EQ preset generated in one limited listening environment (in the car) in another completely different one?

Clicks and pops seemed to happen with high gain.

If you cannot select below 50 Hz then it is likely that the interactions between the various wavebands (Q and fc) means that the "envelope" generated by each band's output filter interacting with their adjacent neighbours means that there is no need for 50Hz band compensation.

However, it could also be that if you have a band on the equaliser displayed with an fc of 50 Hz, and the UI prevents you from accessing it to manipulate it, then it's a BUG.