Never seen this one before:-
Project has a single instance of Reaktor with the Metaphysical Function ensemble loaded. Nothing else. No effects. Just the synth tracks (audio and MIDI) and the master buss.
I had just armed the audio track for record and then pressed the record button.
Problem reporter did not show.
I had to unplug my OCTA-CAPTURE to release the SONARPLT.exe
A second SONAR program icon appeared in my task bar title HUDNowTime and if I hovered the mouse over the icon the Now Time marker appeared.