Rear brakes hanging on

Hi,
I have just completed my full rebuild of my disc (BUDD) and drum brakes on my 68 New Yorker
NOTE.. I used two left Budd calipers and just swapped the bleeder and brass feral to the other hole on one caliper which gave me a left and right)
The brakes are working well apart from an issue with the rear drums.
I have new rear shoes, new return springs and hardware, new wheel cylinders (correct disc brake ones), and drums machined and new rubber hoses (all 3) all backing plates cleaned and...

Rear brakes hanging on