While I can’t be certain, that document, and the annotations on it, do appear to be loading and rendering properly.
Note in the attached screenshot that I’ve opened the right hand side menu, and I’ve selected “All” (as you should be able to as the teacher), and “Whole document”, which are not the default settings for the filters when the document is loaded.
With those options selected, I see a good number of annotations. If you try those steps and still don’t see anything, I suspect either that the group name you’re using are in fact different while appearing the same (different puntuation, capitalization or whitespace), or that some annotators are not checking the box.
In any case, I will send you a full download of all of those annotations for your perusal, including the groups they were shared with.
Thanks, by the way, for checking other posts before adding this question – that’s most appreciated!