I am working on a WPForo Q&A forum. There is a problem where the permalink to an attachment does not work if the attachment has a ".txt" extension.

• Other attachment file extensions, such as "png" or "jpg" work fine. Users can access them using the permalinks that the WPForo plugin assigns.
• "txt" is in the list of allowed extensions in the WPForo settings.
• I confirmed that the "txt" attachments do get saved to the server.
• I can access the "txt" attachment directly from the web, just not using the permalink that WPForo assigns to it.
• My forum can be found here: https://community.onenetwork.com
• The WPForo plugin version is 1.8.4.
• The forum also has the plugin "wpForo Advanced Attachments" from gVectors installed.

Please advise on how best to solve this issue.