While working FT8, I occasionally want to use the Halt TX button.  I've found that it only works properly about 50% of the time.  Sometimes when I click on Halt TX, the Enable TX button changes color from red to gray and my transceiver beeps, but it continues to transmit.  It will continue to xmit until the current message is completed.  I can force it to stop by clicking on Enable TX, which turns red, then re-clicking Halt TX.  Not a serious problem but wondered if anyone else is having this issue.
I am using WSJT-X version 1.8.0 and JTAlert-X version 2.10.4.   My rig is a Kenwood TS-590SG connected to a VSPE RS232 port on a desktop PC running Win7-32.  Rig control is configured via OmniRig   Serial port speed is set at  57600 baud.  Audio is supplied through a SignaLink USB.  I've used this same setup for years while operating JT65 & JT9 and never had this problem.

Gary - AC6EG