Those JS console errors look worrying but it seems you have the combined/compressed JS cache turned on and I would turn that off while troubleshooting.

icons flat? Do you mean the Add files and/or the Start Upload button? If so a common cause of that is a plugin (or WP theme) making use of the unsupported Bootstrap JS/CSS libraries. So have you added a plugin or changed your theme to make this possible?

a link to site could be useful to look for conflicts..

I have tried it both ways, as far as combined/compressed JS and related clearing. I have deactivated just about every plugin and switched to WP 2017 theme. Will keep plugging away at it.

https://canvascampers.com/forum

nothing obvious jumps out there…   no obvious conflicts or bootstrap…

but of course cannot actually try…  so I guess the next step would be to provide us some temp credentials so we can try uploading and see if anything becomes clearer… if that works, please pm the details and link to this topic to both Yellow Swordfish and Mr Papa…

Does this happen in any particular browser?  have you tried more than one?

It’s consistent across all the major browsers (Edge, Chrome, IE11)

I am pretty sure this is a theme issue as I did a test roll back to 3 weeks ago and it works. Looking at the differences between 3 weeks and today, only the theme had an update.

Let me knock on Themify a bit. I will setup credentials anyway for you.

Just added: Looks like Upload works for a normal/subscriber user, so it much be all the extra javascript going on for admin users (probably from the theme as it has a builder that can be activated on any page).

does it work if you switch to the wp default theme?  would be another data point…

edit:  eh, guess the theme rollback answers that… 😉