Dear S.B. Disanayaka,
Good day, thanks for querying in this forum, we’re happy to help you.
From your description, it seems that you want to integrate JIRA with SharePoint, however, you encountered the issue when using JIRA connector.
If my understanding is right, we’d also love to help you, since our category focus on general troubleshooting and built-in features in SharePoint Online, the question you mentioned is related to third-party app, we’d suggest you go to related community to post a new thread, which is specific channel to handle such situation. The engineers in related team will focus on your specific scenario and provide specific suggestions. They also have enough environment to help you test it. And you can also refer to the suggestion below to JIRA community.

For your reference: Jira and Share point online integration issue - Microsoft Q&A
If the scenario above is not consistent with yours, you can also post back and point that.
Thanks for your cooperation.
Sincerely,
Sukie | Microsoft Community Moderator