I had this experience as well i found out that if you paired your for example xiaomi sensors first and than IKEA lamps for the meshing network it wont mesh. I than reset my all Zigbee devices and paired first the ikea lamps and than the xiaomi sensors. Than after pairing i Pulled the plug of homey making sure its a cold restart not an reboot. After homey is fully restarted i went to the development page https://developer.athom.com/tools/zigbee and after a little time the mesh network is visible.
Hope this could help you out with the Zigbee meshing issue for me it works perfectly now.
