Item showing negative quantity on Material Workbench even after gettign consumed by Parent assembly.

I have created a job of 1 quantity of parent assembly with on hand qty of child item as 3. When we see On hand quantity on material workbench with detailed tab for child component after job completion, we see  3 quantity in Source Subinventory(WHSE) & -1 quantity in Supply subinventory(WIPSTAGE), but it sould have shown as quantity as 2 in Source Subinventory.

I have not defined Source SI in Item, nor Supply SI in BOM. But only defined Supply SI in WIP parameters.

All transactions managers are working & there are no pending transactions for the job.

All items are Assembly Pull & I do not do Component Pick Release for the job. But if do a Component Pick Release it will pick Items from Source SI, but when I do not perform pick release it picks from Supply SI.