Seems like it has to be either the return spring, the brake shoe, or wheel cylinder on the left rear is hanging up?
If you can get the drum on to start, then obviously it's retracting initially, but then is not retracting after that.
Break it down again and see if you have a burr or some obstruction/snag on the shoe itself. Put the old shoes back on to see if the problem goes away which wuold confirm that the shoe is the problem, not the wheel cylinder or the spring. It is clear that something is preventing that LR from retracting properly.
Don't drive it any more until this is resolved or you will be adding new drums to your parts list.
