Lightroom won't shoot tethered when in mirror lock-up mode

Lightroom Classic tether function was finally working without issue, but after latestest update (14.1.1) will no longer fire via the tether shooting panel when camera (Nikon 850) is in mirror lock-up mode. The other functions work fine, i.e., shuutter speed, aperture, ISO.. all communicate with camera and adjust, but after first click of shutter release (via tether panel) camera just locks with "PC" on LCD. 

OS: Win 11