Hello Rick,
I´m running it on OSX 10.14.5 (18F132 - Mojave).
Let´s say I´m drawing a simple square and then click on the preview icon in the top toolbar (just like in some simple light burn tutorials on youtube) then just nothing happens. It´s not like something is crashing, it´s just not working.
Alt + P is also not working and under tools the same.
I just thought it´s maybe because no laser is connected or set up.