Just stumbled on this thread after experiencing a very similar problem with a 2477D (v.45) and ISY-994i (software 5.0.16B).
Throughout this switch's lifetime (months if not years) it has been totally silent on local button presses. This morning, I did a factory reset on the device. Still silent, as expected. Then I did "Restore Device" from the ISY-994i, and after the restore, I started getting a beep on every local button press. Controlling the switch remotely (i.e. from the ISY admin console or from a scene) remains silent. I've done the factory reset + restore device cycle several times now with identical results (no beep before restore device, beep on local button press after restore).
The Options screen for this device shows "Program Lock", "LED on TX", and "No LED", all of which are unchecked.
This particular device went through at least one factory reset + restore device cycle under older ISY-994i software (probably 4.7.3), and that didn't enable the beep on local button press.
Any suggestions for easy things to try? (Swapping the switch is possible although something I'm not especially eager to do, since in this respect it was working great up until this morning.)
Thanks,
Bruce.