Shopify show 0 in stock

Hi

I am just starting my store but I've noticed there are some products when I import them from Aliexpress through Auto Ds, the next day I realise in my store that they are are out of stock, but when I check the seller it shows it still in stock.

I am wondering what causing that?

The second question is: shall I request sourcing product through Auto Ds even when I don't have any sells yet? Or its not worth it at this stage? As I am not sure if doing that might fiz the problem?

Thanks in advance