Hi Malay,
LOSC can only be triggered for task with Handling units.
Try creating a Pick HU for the partial qty that you have picked and perform the transaction in RF.
Because in RF all task confirmations are done in 2 steps
i) Source to resource and
ii) Resource to destination. Since the resource to destination has HU (pick HU) it may trigger the LOSC.
I had a similar requirement where the source HU is not proposed for that storage type but i had to trigger a LOSC after picking . Whenever we executed the transactions through desktop it wont trigger the LOSC. But when the same task was performed in RF it showed a different behavior as explained above.
Regards,
Venky