Resource files not showing on Ubuntu 16.04

[ChrisW67]

So you have built on 18.04, made a deployment package on 18.04 using a third-party tool, deployed that package on 16.04, and you do not see the SVG icons.

If you are using the QRC file correctly then resources are built in to the executable; they cannot be missing but they will not be files in the deployment bundle either. If you are explicitly loading them, then you should be referring to them by the pseudo-path "qrc:///images/someicon.svg" and not some relative path like "images/someicon.svg"

Check that the third party tool has placed ".../imageformats/libqsvg.so" and/or ".../iconengines/libqsvgicon.so" in the deployment package. If it hasn't then there are options to force it to do so.