Yes, there was a update in the firmware for improving something with zigbee if I recall correctly, but offhand I don’t know what that is. I’d probably submit a support ticket through the mobile app or email.
If I were you I’d add a repeater or two based upon the number of r devices you have. Since you have Xiaomi devices, I’d go with IKEA’s outlet for a repeater because from what I’ve read in the community those seem to work very well with those sensors.
I don’t have any of these sensors yet, but a quick search came up with a few posts. Maybe these can help you: