Hi @Fink - welcome to the community!
If you’re using a third party app for your Back in Stock alerts, it will depend on the developers of that app to implement those functionalities. Most apps that integrate with Klaviyo lets you select a List you want subscribers to be subscribed to, and set their marketing consent to “Subscribed.”
Do you mind sharing which app you’re using? Perhaps its in their documentation or buried somewhere in their settings or configuration?
Also, as a side note, Klaviyo does have Back in Stock functionality that works with Shopify in case you’re not aware. You can take a look at the installation documentation here:
HI @Fink thanks for posting in the Klaviyo Community! Without knowing the app you are using - the likely reason your subs are showing as not subscribed is because the consent they have given is implicit - they want to receive emails about Back In Stock items, but they haven’t subscribed to email marketing from you other than those emails.
Katherine
Thanks for the replies, the app is Restock Rocket. I have retested this process again today and this time the test contact was added to the correct list and marked as subscribed. I’m not sure why it’s working today but either way I am happy :)