Bug? Highlights from iOS file editor + pencil not showing up in editor


I’ve uploaded to paperpile a PDF that i annotated (drawn highlights, not tied to OCR’d text) with the ‘files’ app in iOS. When I load the file from the viewer, it has no annotations. I checked the forums for a similar thing but don’t see anything. Does anyone know if this is not supposed to do this, supposed to do this until a fix, etc? Thanks.