Replied via email, hope we'll get to the bottom of this!
My 1.6 will not load either.
Please download the latest version 1.6.1 that should hopefully fix the startup error: https://lesspain.software/kyno/download/
Let me know if that helps.
Downloaded the current free trail Mac
and un-zip it. Double click on the app icon and it loads to the splash page and halts.
Any help - thanks!