Okay I have a pretty crispy workaround, but it works.
I am using ACF Pro 5.7.11
In the old thread find the first reply by shaun where he has a code block. Here’s the link:
https://support.advancedcustomfields.com/forums/topic/custom-fields-on-woocommerce-product-variations/
Use that code in functions.php or wherever.
In ACF setup whatever custom fields you need, but in the rule select product instead of product_variation because that option isn’t present.
Go to the ACF Tools page and export the .json of your custom fields. Open that file with a text editor and scroll down to the “locations” section. Simply change the “value” from “product” to “product_variation” and then on that same tools page re-upload the file. You should see custom fields in your product variations drop downs now on variable products.
We were also using that old script, but updates have broken it for us as well. We used this to display extra info on invoices and sort the order of products on our invoices. We have about 2000 unique items, most of them colour variations of eachother, we need this functionality back asap or to revert to an older version of ACF.
