Stencyl 3.5 not opening

I just downloaded the latest build of 3.5 but when I try to open it on my mac it just quickly minimizes after double clicking it.
I'm on High Sierra 10.13.5.

Do you mean the application crashes/closes immediately?

If so, there are instructions on the nightly download page for that:

Mac Users - You must do this to run the app.

If on Mac, drag Stencyl.app out of the folder and back in it again if the app does not launch. This only affects the private builds and does not affect our public builds.

Thanks! That did it!