Downgrading from 1.13preX resets controls to defaults

I mostly use the 1.13 pre-release for single-player worlds, but all the servers still use 1.12.2, so I switch between versions regularly based on the situation. Despite being a subhuman creature known as a "casual", I use decent equipment typically reserved for "real gamers", most notably a wireless keyboard with no middle mouse button. As such, the "pick block" key is set to M instead. After switching between versions, trying to pick a block in Creative mode does nothing, and when I open the controls menu it's been reset to the default. Basic logic says that it's more likely to be a full reset than just the one action, but I can test that theory if needed.