Thanks. I did contact Authy and I have attached the reply just in case anyone else is having this issue.
Starting June 1, 2016, all new watchOS apps submitted to the App Store must be native apps built with the watchOS 2 SDK or later" > The Authy app version 19.5 is built with watchOS1 SDK and we need to update it to watchOS2.
When users report that the watch is not up to date with the iOS app, we have some workarounds:
If interacting with the iOS device, put the iOS app on background or force close the Authy iOS app
If Authy app watch is open, put the watch app on background or force close the app
If the above steps do not trigger the synchronization, re-installing the Authy Apple Watch app will most likely trigger it.
For users that have a large number of accounts, the synchronization will take more time since the payload that will be sent to the watch app is bigger. The system will deliver the data as soon as possible to the counterpart app, but it will try to save battery life if needed hence the delivery is not guaranteed to happen immediately.