Mojave external USB eDrive not boot

I have two computers newly installed Mojave and I have created new eDrive on each on an external USB drive not formatted to AFPS. The external drives are Max OS Extended (Journaled). I can create the eDrive alright, but when I try to restart to the eDrive, it boots the normal disk, even though I set the startup disk to be eDrive. Does the external drive need to be case sensitive?

I have looked existing TechTool Pro 11 topics and not seen discussion on this. Have I missed something?
Running MacOS Mojave 10.14.5 and TechTool Pro 11.0.3.
Both of these external disks were booting High Sierra eDisk before I removed/created a new eDisk.