Hi Tim,
Thank you for contacting us. I'm not sure what would be causing the iCloud syncing to fail, but I will try to help. As long as both iOS devices are signed in to the same iCloud account in iOS's Settings, then syncing should work. With iCloud syncing, mSecure hands off data to your iCloud account, then that data is synced over to any devices that are signed in to the same iCloud account. After the handoff of the encrypted data, mSecure has no control of the actual syncing of the data, and if the devices are not signed in to the same iCloud account, the sync will fail even if you're signed in to the same mSecure account on both devices.
While I can help you with trying to get the iCloud sync feature working, it is worth noting that mSecure Cloud syncing is totally secure, and it's much a much simpler method to use. Each mSecure app signed in to the same account syncs directly to our cloud service, and there is no hand off like in iCloud syncing. If you were open to use mSecure Cloud syncing, it should be very simple to get everything working.
Tim
Everything looks ok all on same account, both set in settings to use iCloud. Even turned off syncing from ver 4 that is installed on both devices.