Two Things:
1) I just had one bottle refilled, put it back on line and the same thing - barely any flow...I disconnected this bottle and hooked up the standby bottle and all was well again, thus the regulator and hose were not the problem...
So I lifted up the newly refilled bottle about 1" off the floor and let it drop once or twice, then put it back in service and no more problem - apparently the OPD's ball-check device got lodged shut when the bottle was filled.
2) For redundancy, the hoses also have a built-in ball check that can fail closed...