Issue with a button in performance mode

Not sure if this is an issue with my skills (most likely) or a bug.
I have a button in a UI that works fine in network mode and activates recording of a movie file out, but as soon as I go into performance mode the button only works the first time but not for any consecutive triggers. When I return to look at the network, and the button is down I can see the select has actually been activated but the Record paramenter is still set to 0 even though the input is at 1. See attached image.

Can anyone help or suggest what might be wrong??
(Build 2018.23760)

Thanks.