I have found a cause for this problem.
On my Ubuntu 18.04 aarch64/arm64 Odroid system it is refusing to read the applications.json file because that file contains accented characters.
I removed the accented characters from the Deja application entry in the json file and it now works.
However this in turn requires an explanation as to why it is not accepting accented characters when that same json file is working on my Ubuntu 18.04 arm32 PI system.