Email handler: Error handling: Could not find a corresponding issue to comment

FYI: the issue identifier was included in the email subject: 'RE: [SCALE] Commented: (IT-1061) some text'. "IT-1061" is a valid ticket, one that can be accessed using /browse/IT-1061 url.

What is strange is that feature used to work but now it doesn't work in both instances that we have (3.3 and 4.4).

The log file contains not information regarding any failure related to that.

An error was encountered whilst handling messages from the mail server
"Citrix" using the handler "class com.atlassian.jira.service.util.handler.NonQuotedCommentHandler".

The error was:
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"Could not find a corresponding issue to comment and Create Issue Handler is not selected."
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The error and the email that caused the error are attached to this email.