Hello @RFragola,
Thanks for your question and for the description of the issue.
I’m not aware of this kind of report before, but it seems the issue is a bit difficult to replicate, as it occurs only for one of the journals in the same multi-journal OJS platform.
Could you please let us know which version of the plugin you are using?
Keep in mind also there can be some lag time between a DOI being registered (or updated) and that same item being indexed (or reindexed with updates) in our REST API. The XML API and DOI Handle system are updated immediately, but those same changes can take several hours or sometimes longer to appear in the REST API and other services downstream from there, such as Metadata Search.
If you can provide me with a submission id or copy of the submission log I could take a look at it and see if I find something that could be useful to better understand the problem.