Hey haggler2,
Thanks for feedback! I agree that this might be confusing, so I have entered a feature request to add a Save button to Level Blueprint Toolbar for developers to consider. I will let you know what they say as soon as I get an update.
I was not able to reproduce greyed-out Save On Compile option, however. Is this still occurring in 4.7 Preview 7? Is this happening in binary build from Launcher, or have you built from source?