Curious. I thought I may have misunderstood, but clearly not. Thanks anyway.
That's what I did, using an Rpi running OSMC, attempting to replicate your workflow. Having trawled though the thread and even bought/setup/tested an arduino in preparation for buying the Vero4k, knowing my current GPIO driven setup was out in favour of USB.
The only difference, I think, is I used an Rpi 3 instead of 2.
As we're dealing with classic most of it is as old as the hills so it shouldn't be that my git clone is out of date compared with yours (and yours is long standing too).
I'll just have to try building old classic again when I get chance and who knows... Not to worry. Certainly not my biggest problem right now!