I'm trying to build a collaborative Map Tour with 11 collaborators. I am the Owner and sign in to ESRI through an institutional membership; they all also sign in through institutional memberships with the Publisher role. I created a Group and shared the Story Map application with them; I want them to be able to publish to the Story Map rather than the base layer. They can see and click the blue Edit button and also click to Add a tour point.
However, they cannot upload any image files; they get an "Error Uploading the Picture" message. I've tried uploading the same images with no problem, so it's not an issue with image size/quality. I've tried changing their status from Member of Group to Group Manager but that doesn't solve the problem. They've tried multiple browsers, to no effect. And they've completed all the other information in the tabs under Add, so that's not the problem.
Any ideas? I've looked here and here and even here. I'd be grateful for any insight, and apologies if I've missed a post dealing with this somewhere. I love the tool (though miss the Crowdsource option) and hope to use this with my classes going forward, but obviously need my students to be able to contribute directly if I'm going to do this. I know it's not a standard use, but the information makes it sounds like it's in theory possible?