ONS is easier to use. I also had the same issue with a micrologix 1200 where the OSR has a storage and output bit. What I did, and it works:-
the OSR command is an OUTPUT, with any bit (say B3:0/0) for "storage" and any bit for the "output" (say B3:0/1). The B3:0/1 is the input for the rung you want as OSR. Try it:
eg
[ ]------------------------------------Storage = B3:0/0
Ouput = B3:0/1
B3:0/1-----------------------------------------( )