Failure to submit to Crossref

Some of our Crossref deposits are failing due to an apparent issue with the parent DOI being the same as the component DOIs. Looking at the XML results, this does not appear to be the case and I’m wondering if someone here can identify why this is failing.

Steps I took leading up to the issue
Choose an article
Submit to Crossref by clicking the “deposit” button.

What application are you using?
OJS 3.1.0.13

Additional information
The XML returned from the plugin is:

Successfully updated in handle

<?xml version="1.0" encoding="UTF-8"?>

<doi_batch_diagnostic status=“completed” sp=“bstn-prod-ds-03”>
<submission_id>1665038937</submission_id>
<batch_id>_1736255467</batch_id>
<record_diagnostic status=“Success”>
10.18849/ve.v2i4
Successfully updated in handle
</record_diagnostic>
<record_diagnostic status=“Failure”>
10.18849/ve.v2i4.111
Failed to process component (The parent DOI 10.18849/ve.v2i4.111 matches the component DOI! This is invalid, they cannot be the same.)
</record_diagnostic>
<record_diagnostic status=“Failure” msg_id=“48”>
10.18849/ve.v2i4.111
The parent DOI 10.18849/ve.v2i4.111 matches the component DOI! This is invalid, they cannot be the same.
</record_diagnostic>
<batch_data>
<record_count>3</record_count>
<success_count>1</success_count>
<warning_count>0</warning_count>
<failure_count>2</failure_count>
</batch_data>
</doi_batch_diagnostic>

I’m not sure why this is happening, and it only affects some of our historical articles. I would be interested in hearing any advice on how to resolve this issue.

Many thanks in advance,

Anthony