Communication with controller failed - lasertube stays off

RDC 644XS / RDLC-V8.01.62
USB, Lightburn 1.0.04, Mac

Hi there,
“Communication with the controller failed” appears in the machine settings. communication with the controller only works with “find my laser”.
the control of the laser head works perfectly but the laser does not receive any power, i.e. no cutting.
with RDWorks V8 the lasers are switched on, but i would prefer to work with lightburn.

thank you for your help, marc