Will only let me connect to personal ad accounts

After ensuring through Facebook support that I have admin access to a client’s Facebook Page through their business manager (not just through ours) I have run through set up again.

When connecting the plugin through WooCommerce to Facebook I get the following issue…

I can select their Business Manager, select their Facebook Page, select their Instagram page and select the product catalogue we created for them – then when it asks me to select the Ad Account to use, I am only seeing Ad Accounts connected to my personal Ad Manager, not the Business Ad Manager I am trying to use.

Why is this?