@kopczas thats a good question. I do not really know about the MX4 Pro, but I read something about the MX4. Those who tried using it with TWRP ended up to hardbrick their device. So best is to install Flyme always over the stock recovery.
Funny thing, I installed twrp like @Rey suggested. reboot into twrp, did nothing I just looked what is that, then restarted the phone. First time I got bootloop, for the second it started optimazing apps… why??