Thanks for your question. Are you encountering this issue with multiple articles of just this particular one?
I would suggest confirming that you have the DOI properly configured to assign DOIs to articles and all other relevant types and that you have all your Publisher information - abbreviation, initial, online ISSN filled.
We have the same problem.
An editor was working on on an issue before we upgraded to 3.2 and after the upgrade 3 articles were submitted to the issue. these articles do no have a doi.
We have tried to unpublish the submissions but are unable to add a doi.
There was no problem before the upgrade and all the submissions before the upgrade in the same issue have a doi that has succesfully resolved.
I see that this is solved by changing the doi suffix pattern. Is this a bug that will be fixed? or do we have to change the suffix patterns for journals that do not use volume nr? even though the journal has not done so before?