I have been having various issues documented at this link and hopefully fixed as per this link
In summary - was having issues with a multi-purpose sensor, which led me to reset zigmee mesh, which screwed everything up, which led me to factory reset hub, after which reset sensors would not get discovered and then finally fixed as per procedure in above links.
Some points to note - I have a case open with support on checkinterval going from 720 to 7260 seconds for certain sensors which then leads to them being stuck in open/close/active/inactive and eventually going offline. Support was not very helpful on this and had no idea on checkinterval issues. After the firmware update these issues probably worsened which led me to resets. etc detailed in my links above. The offending sensors shipped with LIXING batteries, however switching to panasonic after the issues has not helped. Putting lixing batteries into working sensors screwed them up as well. However now after the full reset and rebuild, things seem fine. Did have an osram led bulb in my network, which I got rid off before the rebuild!