This was me trying to open the menu so I could turn on ground power and ground air supply. It previously worked fine but I don't remember exactly when, probably a couple months ago. I have no mods installed and I never installed any mods previously. I do have SRS running and it was connected when I originally encountered this issue. I tried unbinding and rebinding the Radio 1 HOTAS button (hat switch down) I use that is equivalent to "RAlt + \" in DCS to no avail. This is different from my Radio 1 PTT button (hat switch forward) in the Tomcat, which I have bound in SRS, and in DCS as the SRS button IIRC.
I have the same Radio 1 button (hat switch down, same bind as "RAlt + \") bound on planes like the Hornet and it works fine there. The Tomcat has always behaved a little differently with SRS than other planes so maybe there's some weirdness going on there.
My SRS binds are:
hat press in: PTT
hat fore: radio 1 select
hat aft: radio 2 select
DCS radio binds
hat down: radio 1 (same as "RAlt + \")
hat up: radio 2
In the Tomcat, rather than select radio 1, hat fore will instead transmit, and hat press in does nothing. I'm pretty sure this still worked fine even after in-game voice was introduced. I have not used in-game voice to date.