Checked the network setting and all, even tried to set to NR only then got no signal at all.Check the bands with Network Signal Guru then to make sure they're actually enabled. If not then try flashing the global firmware on top of the .EU rom. If neither works then you'll have to contact Xiaomi to get them to fix it in their rom. Then it will trickle down to the .EU rom eventually.
And you're sure the phone isn't just set to LTE preferred in the network settings? (Or hidden dialer menu *#*#4636#*#*)
You haven't really stated anything you've tried other than flashing .EU.
What do you mean by flashing global firmware on top of EU Rom ? Mind to elaborate on this please. Thank you.