The most problems of roms depends to interrupted downloads, especially when many users are downloading at the same time, so it´s worth to check the md5. I have had problems like many others with updating twrp on my ultra, because i didn´t know, that there is no more a recovery partition on this device. On my devices of Xiaomi before (last Mi 10 Ultra) this problem does not exist. Now the downloaded twrp.img must be copied to internal storage and installed from there by order "install recovery ramdisk". Updating twrp is easy, downloading, copying into internal storage and instll it in the same way as before. So i´ve updated from skkk 6.6 to 6.7 without problems. And my rom runs also perfect (the things i use).