The importer is part of WPML. I have reached out to them as well, and I’m waiting to hear back. I feel that it has to do with how they are adding the post meta data. The problem is, they already told me, which I knew they would, that ACF is not a supported plugin. However ACF says it is on their side. I just need to figure this out, because I have a lot of pages to import, so any help or ideas are greatly appreciated!
