Thanks for trying that, that's appreciated. I've included a test file as an attachment to this post. Could you try uploading it to your forum and let me know if anything has changed? No need to deactivate the plugin before you do that, the change will take effect either way.
EDIT: I've removed the test file, since it didn't work for the reporter on GitHub. I've also tried a fresh install of MyBB myself and reproduced the issue, so I can test changes directly (which should make life A LOT easier for all of us).
EDIT: I've removed the test file, since it didn't work for the reporter on GitHub. I've also tried a fresh install of MyBB myself and reproduced the issue, so I can test changes directly (which should make life A LOT easier for all of us).