So, after reverting different commits touching the patchwork-internals it would seem that this is the commit that broke it:
Make standard 16 happy.
Seems some of those linting changes were not so benign after all. 😐
But hey, it works for me now, with the Sophisticated Bug Busting procedure linked above. 🙂
Now I just need to understand what exactly broke it and then the fix should be simple.