The new eBay auto-fill coupon feature breaks when the master post lists multiple coupons. See for example, these master coupon posts.
https://www.ozbargain.com.au/node/472089
https://www.ozbargain.com.au/node/470435
The auto-fill button enters all the multiple coupons into the coupon box, and it is not immediately clear as to which code is correct for the deal in question. There needs to be a way to select individual code from multiple coupons.
Perhaps then the solution is to break apart master coupon posts? Who should do that? The OP, the Mods, the Power Users?
The meta info (title, expiry date, etc) is taken from the post itself, which only allows one set of such data. Therefore ideally the concurrent promotions from marketplace such as eBay should not be combined. Otherwise more structured info needs to be entered on the post itself, which is not desirable.
And here we have an example where auto-fill breaks down. You can't tell which coupon is active until you visit the product listing on eBay: https://www.ozbargain.com.au/node/472143/revisions/978172/vi…
There are a lot of other issues when people put multiple coupon code in the field, which is why we prefer people to use only one coupon code there especially for master coupons where a lot of other deals will come out from that.
That further complicated things when individual coupons have different descriptions, for different sub-stores on the market place, have different expiry date, etc.