Yes , I use a joystick PTT button but I have also tried using a keyboard hotkey with no better results.
I want to explain what happens in detail.
On vPilot , when I press and hold the hotkey the transmission starts normal with the TX sign turning blue , but once I take my hand off , the TX stays blue and transmits for a complete 5 seconds before it stops , leaving a plain "zzzzz" noise at the end of the transmission.
I use VRC as well and they both are very similar but I do not have the extended delay.
I can paste a short clip of the problem if you wish.