This problem first showed up in October 2015, and was solved by Apple later in the year. All HomeKit accessory manufacturers were affected at that time. Now the problem has resurfaced in rare cases and is not related to our Eve app, or any other HomeKit enabled app.
The symptom is that the Eve app is stuck, with the error message "iCloud Data Sync is currently in progress…", and when you open the Home app from Apple, it is stuck as well and displays the error message "Loading accessories and scenes…". Both of these error messages are due to the same problem: the iPhone is trying to resolve a conflict between the home configuration that resides on your device (iPhone, iPad) and the configuration that was sent to it via iCloud sync.
We have reached out to Apple for help and Apple has a solution, but it takes a while, from 30 minutes to an hour. It's not too complicated but the only solution we can recommend for the time being. We assume that you have a backup of your iPhone.
- Make sure iCloud keychain is enabled in iOS Settings > iCloud and the latest iOS 10.3.x is installed. Make sure to use Two-factor authentication for your Apple ID (https://support.apple.com/en-us/HT204915).
- Force quit all apps, then reboot the iPhone.
- Connect the iPhone to a power source.
- Goto iOS > Settings > Display and Brightness and set Auto-Lock to Never.
- Open Apple's Home app/
- You'll see the error message "Loading accessories and scenes".
- Wait for about 30 minutes with the Home app open.
- Eventually, a message should pop up asking you whether you'd like to "Reset HomeKit configuration?". Tap Yes.
- The HomeKit configuration on your phone will be deleted, as well as the configuration in iCloud.
- All of your Eve (and other HomeKit devices) will need a Hardware reset.
- Start Eve and do a fresh setup - add all HomeKit devices back to your configuration.
Depending on the number of devices this may take a while, you'll be starting from scratch, unfortunately.