Hiya, I've kept it in development because I'm constantly adding it to it, new issues when they're out etc. it's not really a "done project". Should I change that?
Viewing post in Magazine promotion
Each issue is its own itch.io project page - so you should set every issue to "Completed" when it that issue is completed. Metadata is per project.
Even when a project has been marked as "Completed", you can still make updates to it if necessary (although it would be weird to add new articles to a back-issue of a magazine imo, but you do you)