I know this is an old post but hopefully can help someone out with a similar issue
I just upgraded to 5.13 and am having the same issue with m3 & the GUI “laser” button not firing the laser manually when in tool 111. Reading a bit on masso’s site m4 is listed to “laser on immediate” while m3 fires “laser output enabled with motion” I’m guessing this changed between my last version (5.10 I think) and 5.13
The odd thing is the laser on button must still be using an m3 because it highlights but does not turn the laser on till there is x-y movement (apparently via g-code as jogging it with an m3 on does not seem to turn it on either)