If it's any help, I had the same problem.
I used the F2 key to apply reverse thrust and the F1 key to cancel it.
Each time, all four engines stopped.

However, I found that if I use the F2 key to apply the reverse thrust but
use just a very small amount of throttle to cancel it, reverse thrust is cancelled but the engines do not stop.

I don't have any fancy hardware, just a keyboard and a venerable Microsoft Sidewinder precision pro that has seen better days.

Regards,
Nick