Machine coordinates don't show

[letrow]

I use LaserWeb in my home-built machine with a BTT SKR Pico controller running grblHAL Connection is via the BTT's UART which is forced into MPG mode by python script triggered by a systemd service and neatly shows up in LW's connection dialog as /dev/ttyS0. Everything works well except that the X and Y position in LW remain stuck at 0.00 instead of reporting the actual machine state.
Apparently LW does not query grblHAL for its status or expects grblHAL to periodically transmit its status.

[letrow]

Edit: I used $481=1000 to enable 1-second interval automatic status reporting in grblHAL and when checking with a terminal I get the automatic reports OK but they don't show in LaserWeb.