Hey @EricL, thanks for reaching out, definitely understand the frustration here regarding the limitation.
I’ve added your feedback to the feature request I opened on my end. While I can’t share any updates on timing or if/when this might be implemented, I wanted to thank you taking the time to weigh in here and to let you know I’ve logged your feedback. Thanks again, it’s really appreciated.
Huuuge limitation of this API. Really really frustrating. And your AI assistant keeps saying you can. Really annoying. What are you guys doing ?
jumping in here too to express my frustration about this. Further more, the line item properties on bundle items propagate all the way to checkout but they never get saved in the order data. This created a huge issue for one of our clients and the fact that we can not add a line item property not after the order has been paid, is a huge downer.
More info on this post
Hi, also jumping on to this as we have a specific use case that really needs this to be possible.
Our store uses a custom product editor built in-house, with customer designs linked to order line items using line item properties. In order for the product to be changed after ordering, we would need API access to add a line item property to the new item in the order.
Since we cannot, there is no way to reference the design with links on the line item in order/confirmation emails etc. We can workaround this in most places by having the line item/order information saved in our app database for the design, but as mentioned by many others, line item properties are the only way currently to have full support for referencing in a lot of other Shopify places like the order page/emails/etc.
I don’t think this would be a very complicated API option to add, and I’m sure the overhead of checking these requests has already eclipsed the work time to do so 
I’d greatly appreciate this being escalated to whoever can get this implemented.
I am also jumping along. I sell machinery, and all of them require serial number registration. I would like to see a line item to input those serial numbers andpossiblyy make them indexed, where we can search them up in the future
Adding my name to the hat… I’m developing a bundle app that leverages hidden cart line-item properties when building and transforming the cart. These line item properties then appear in the order which looks ugly (for a merchant).
It’s interesting that line item properties can be deleted from an existing order in the Admin, but not via the GraphQL API.
Any action/function that can be performed in a UI should also be available via an API.
Another request for this one
+1 from me for this feature