I helped a friend do a setup, we used :

• The latest RPi 3 B+
• Rasperian Stretch with Desktop and recommended software ( from https://www.raspberrypi.org/downloads/raspbian/)
• Software update prior to installation

The initial script failed on dependancies and depracated packages. Just could not get it to work.

Today I followed the instructions on :

• The RPi 3 B
• Rasperian Stretch with Desktop ( from https://www.raspberrypi.org/downloads/raspbian/ )
• no update

While I did get warnings, everything worked like a charm ( well - more or less - I forgot to copy the config.)

I know from another package ( https://octoprint.org/ - The OctoPi ) that some work needed to be done to support the RPi 3 B+ (Newer CPU ? Drivers ? Chipsets? - no really sure). Could this be the issue?

I will borrow his RPi 3 B+ and try again next week if no one else has comparables.