i first tried to flash this over oos 3.1.4 but i got an error 7 saying i should try to factory reset first, what i did after and when flashing it just go to 0% to 100% and when i reboot it is stuck on bootlogo.
I remember having an issue like this 1 year ago and we needed to flash a boot.img but i dont remember is this was for this rom or not
I'll just give you the steps which I always do and which never failed for me so far:
1. Boot to TWRP
2. Make sure the MM Bootloader is installed (which is the case if you were on 3.1.4 other flash 3.1.4)
3. Completely format /system /data and /cache to ext4
4. Flash the ROM Zip, make sure you got no corrupted download
5. Flash GApps
6. Flash the Root solution of your liking
7. Reboot to System (first boot will take several minutes so make sure you are connected to a charger or your battery loaded)
Otherwise only log files can help us