Virtuemart product page hiding drop down on out of stock

[pm4698]

Hi there.

Joomla 3.10.3 and Virtuemart 3.8.8.

I have some parent products with child products having different stock levels. So when I am in product details of the parent product and start picking i.e. colours from the drop down then page gets the picked product without refreshing and you can order the product. Drop down to pick another colour is there. But when you pick a colour that child product has no stock then you see the notify me but the drop down goes away.

Is it an normal behaviour or a custom related one? And if its the 1st case how can we stop removing the drop down?

Thank you in advance