InputEvents seem to be accessible over SimConnect only when MSFS is switched to Developer Mode. With the sim in normal mode, Input Events cannot be enumerated. SimConnect doesn’t throw an exception, OnRecvEnumerateInputEvents just returns an empty list.
Without the actual hash code it is not possible to use the InputEvents in subsequent Get or Set actions.
Repro steps:
Switch off Developer Mode and try to read the inputevent list.
This also appears to affect the GetInputEvent and SetInputEvent APIs, but oddly not the EnumerateInputEventParams API.
I built a test app that has a textbox to put in a hash. If I run MSFS 2020 and do not have developer mode active I can successfully get the event params for a hash (e.g. 8822175623453154861, the parking brake on the CJ4), but I cannot get the current value and can’t set the current value.
As soon as I enable developer mode and do a quick reload on the aircraft I can get and set successfully via the hash.
I noticed one other thing recently. It seems that for some aircraft (for example the Aerosoft/FSS EJets), subscribing to “all” InputEvents (ID=0) doesn’t return anything, or at least not predictably. With other, more default, aircraft, when I press the button in the cockpit, I get a notification for the IE that has been triggered. That doesn’t happen with the FSS planes. Not sure if that is something that they have to address or if it is relevant to you, so I’m just leaving it here.