Sounds like something you could do pretty well with a Trello
You could keep all future ideas in a list entitled something like "To do" or "Future Issues" and when you actually follow through with them for an issue you can move it over. For the current/in-progress issue, you could either make a list for each specific issue (e.g., June 2019) or just a list called something like Current Issue, and drag your items from the To Do list onto the current issue list. Then once the issue is published and work begins on the next, you can either move everything from the Current Issue list to the Done or Past Issues list, or if you use a unique list for each issue, you could just create an e.g., July 2019 list and go from there.
It's easy to collaborate with others. You could assign each card to whoever is working on each item, or just keep a note of it yourself in the card details if you or your contributors don't want to or can't join the Trello board for whatever reason.
Here are a couple mockup images I made to show off what I tried to describe.Software for Managing the Production of a Magazine
This is the generic lists example.Software for Managing the Production of a Magazine
This uses a new list for each specific magazine issue.
And keep in mind that the basic idea behind Trello is to have 3 categories of lists: To Do, Doing, and Done. Of course you can name them whatever you want and modify the basic structure however fits your needs, but you certainly don't need to use the Trello software to do this.
And if you find that Trello is a bit too simple for your needs, you can find something similar but with a bit more complexity in Hack 'n' Plan