Suppose it is passed enough time to have some final decision. @Mali2's assumption was correct - it looks like issue was caused by TWRP. I flashed another one (see links above) and from that moment I haven't any issue with rebooting to fastboot.
Thank you for reply. But ROM I am flashing (12.1 20.6.18 beta) luckily is Android 10 (I aware about compatibility issue with Magisk). Do you suppose it could suffer from Magisk incompatibility?
Hi. I just received Mi 10 and tried to flash it with xiaomi.eu rom (native one - Global which doesn't support 2 SIM). It was pretty hard as it often declined to boot to the system. Finally I able to flash it successfully and ROM detects both SIM cards. But another problem appears: randomly after...