Incorrect file package - missing imsmanifest.xml or AICC structure

I am getting this error uploading a package to my LMS. I have successfully published other courses with the same publishing settings. I use the Articulate zipping tool. I have checked the zip, and there is an imsmanifest.xml on the root of the zipped file. I am at a loss of what to do having read other posts about this issue. I successfully published to SCORM Cloud. The file size isn't big 10,752kb.

My Articulate version is up to date.