Current song display

I have made a Preamp from a design from this website.
It includes a PI3B running Volumio and some code written by the designer which should display the current song title on it display.
Unfortunately it only shows the first, subsequent titles are never shown. They correctly show in the Volumio App and in /DEV , just not on my Preamp !
The code is written in Python and though I can just about understand it, correcting it is beyond me. Fortunately logging is written in the code so with some additions it should be possible to find where it fails.
Can anybody help?