> I cannot insert images into a channel w/ a customer via drag and drop

Yup, we struggle with this. Seems to have to do with needing to pay for seats in order to have file-sharing allowed (but you can still paste Sharepoint/Onedrive links). Can't share files if there's even a single external person in the chat/channel. Forced us to buy another seat subscription. It's great!

That kinda makes sense (and thank you!), but I think the comprehensive incompetence is thus:

1 - fails 2 - w/ no useful feedback to user; 3 - I couldn't get support to tell me why (fine, small account), but the customer with 900 licensed seats couldn't either

Fortunately, said customer has come to the realization of how very bad it is and is hopefully migrating to Slack.