Redmine

Redmine Knowledgebase Help - Files not showing

I have done a migration from this version, details below:
Environment:
Redmine version 3.2.1.stable
Ruby version 2.1.7-p400 (2015-08-18) [i386-mingw32]
Rails version 4.2.5.2
Environment production
Database adapter Mysql2
SCM:
Subversion 1.8.11
Git 2.5.1
Filesystem
Redmine plugins:
chiliproject_look_and_feel 0.0.5
clipboard_image_paste 1.10
redmine_agile 1.4.0
redmine_checklists 3.1.6
redmine_issue_templates 0.1.3
redmine_knowledgebase 3.1.0

To this version:
Environment:
Redmine version 4.2.2.stable
Ruby version 2.6.8-p205 (2021-07-07) [x64-mingw32]
Rails version 5.2.6
Environment production
Database adapter Mysql2
Mailer queue ActiveJob::QueueAdapters::AsyncAdapter
Mailer delivery smtp
SCM:
Subversion 1.14.1
Git 2.32.0
Filesystem
Redmine plugins:
redmine_checklists 3.1.19
redmine_issue_templates 1.1.0
redmine_knowledgebase 4.1.1

Plugin in question:
Knowledgebase
A plugin for Redmine that adds knowledgebase functionality
https://github.com/alexbevi/redmine_knowledgebase

All the issues and everything has migrated over no problem, however I have an issue with the Redmine Knowledgebase plugin where the files are not showing.

Referring to the screenshot, Old Remine Files - you can see the files in the old system.

However on the new system, if you go to the same kb article there are no files in the files tab - as per screenshot New Redmine Files.

Note in the screenshot you can export this KB article to PDF, and in the PDF you can actually see the files are there - but are not being displayed on the KB file tab.

See export kb files screenshot.

How do I get these files to become available in the KB articles? any ideas would be appreciated - I can confirm the files are in the /files directory of Redmine. Just wont be displayed for some reason.

Cheers