Fenix 5 up/down button in Connect IQ Simulator

Developing on macos 10.15.3 using connectiq-sdk-mac-3.1.8-2020-05-01-5a72d0ab2.

I have a widget that's working great in fenix 6 simulator, all buttons as expected.

Switching to fenix5 simulator the select and back buttons work as expected but up and down buttons do not seem to fire at all.

I have tried adding an onKey() handler to my delegate and that doesn't get called at all for the up/down keys.

Is the simulator broken or do I need to do something different in my delegate for the fenix 5?

Thanks