thank you for answering.
Sorry, I forgot: The Rig is a TS-950SDX connected to the PC via a virtual COM port 5 using a MicroHam USB Interface III.
In parallel to WSJT-X I am using HDSDR for an IF based waterfall diagram and monitoring. The SDR used for this is a SDRPlay RSP2 which is connected to the 8,83 MHz IF out of the TS-950SDX.
HDSDR also supports OmniRig which allows multiple software programs accessing a Rig. The connection from HDR (which unfortunately doesn't support OmniRig) to the Kenwood is done via HDSDR which offers a virtual COM port configured to COM 10 (together with a virtual COM cable configured as a connector between COM10 and COM11), so that HDR can connect to the TS950 via COM11 -> Virtual cable COM 10 -> HDSDR -> OmniRig -> TS-950SDX.
This may sound a little weird or complicated. But before the hardware upgrade it worked flawlessly and I don't see another way to get the desired configuration running.
On the other hand I don't see a reason why this well tried and proven setup shouldn't work just because of changed and even better hardware.
And the show stopping issue definitely is WSJT-X with itÄs error message coming up.
Klaus / DF6NP