For reference, I'm not using the newer cloud solution for content management.
I've read several posts on how to mitigate this issue, and none of the outstanding problems are related.
Tried logging out and logging back in to a different user.
Checked that all of the files are rgb and not cmyk.
Tried on a Mac in Chrome and Firefox.
Tried on Windows 10 in Chrome.
Tried jpg and png. I've even reexported a png with no luck.
Tried at home and at work, where I've been able to upload files successfully for months.
The only file that has successfully uploaded for me in the last two days is a 67kb png. All of my files are less then 10mb.
What else is there to try? It isn't my network(s) or files, its starting to look like the webui is causing this issue.