In the BigWarp help it says:
Landmarks are placed in landmark mode which is entered by pressing and holding the space bar.
For me, MacOS 10.14.6, holding the space bar leads to a flickering “on” “off” of the landmark modes. I just need to click the space bar once, and then let go of it to toggle between landmark mode on and off. Is the help outdated or do you think it is an OS issue?