Inventory Items - Purchase and Sales Invoices are not increasing or decreasing stock items suddenly

I have Manager Cloud edition and it has been working fine. Today I went to check on stocks of certain items and nearly all items are showing a zero balance except those I have made inventory write offs against. Why are the purchase and sales invoices not reflecting the stocks bought and sold suddenly? @lubos please help

Select Qty Owned column , using edit column button.

Thank you. I did this just before you responded and it worked. I am perplexed as to why this all changed suddenly though. I have not selected “Goods Received” or “Delivery Notes” tabs so it makes no sense. I’m just relieved its working though!