Thanks for getting back to me, Steven_ZA.

Since the option for full stock stacking is available in QuickBooks Online Plus version, we're unable to use the normal stock account and create a different one under Other Current assets.

If you want to use the stock account, you may want to upgrade your subscription. 

Here's a reference on how we can upgrade the account: Upgrade or downgrade your QuickBooks Online subscription.

Keep me posted if anything arises.