i'm also running microg and went the same path, so there's at least two of us you need to upgrade your firmware for the fingerprint scanner to work. i had the same issue but after flashing the latest (firmware_V10.0.6.0.PDHMIXM.zip) via twrp it works (including LTE bands).
can any body tell me how to get the full capacity i.e. 64 gb as when i installed lineage 16 official rom on my xiaomi m1 on original software the resulting system is only 32 gb.is there any way to get the other slot storage to system
You wanna destroy your system? That's impossible, a/b system is really good imo, Mi A1 is lucky to have that partition.