homekit configuration 3 weeks out of date

Yesterday lost access to all my homekit accessories. Went to look at it in the app and the configuration was 3 weeks out of date. I had done a significant overhaul over the last 3 weeks. Devices I had added were gone. Devices I had removed were back. Devices I had reconfigured had reverted to an old config (at least according to homekit but not the device itself so of course it could not access it).

Anybody run into this? Any ideas? It was hours of work to recover it so i want to avoid this in future. Anyone know of any way to backup the homekit config?

I have no idea which is the right forum to post this to btw - there does not seem to be one for homekit!