Fenix Chrono compatibility problem

Hi,
I thought that the new Fenix Chronos are fully compatible to the Fenix3 family.
I just tried with two of my old designs to add the Fenix chrono to the manifest.xml file.

While both watch faces are working fine with new SDK 2.1.3 on F3, F3-HR, D2, D2-Titanium both watch faces crash on the simulator with the Fenix Chrono
I get
Failed invoking <symbol>
Out Of Memory Error ...

(This is not the "Too Many Arguments Error")
So my question:
are the Fenix Chronos really 100% compatible with the Fenix 3 family or do we have to check all our old designs if they still work on the Fenix Chronos?

Unfortunately I do not own a Fenix Chrono to test it on a real device.

Thanks a lot in advance for any advice!