This appears to be an Apple side problem for a large number of people. I have half a dozen builds, all for the same version and build number, all displaying "Processing" now for many days. Now builds are just displaying "Created" when the SSH session fails as described above.
No messages here except "Potential Loss of Keychain Access", which is a warning message that occurs every time the application identifier prefix changes.
Nothing in junk mail folders.
Have tried disabling bitcode.
My apps do not use App Thinning, and have not changed substantially since the last uploads.
Same behavior regardless of uploading through Xcode or the Application Loader.
Same behavior from multiple networks.
In the new Resource and Help section of iTunes Connect, there is this statement. I suggest every developer who is having this problem contact Apple as indicated.
Before you can use a build on iTunes Connect, it must be processed. If you’ve successfully uploaded a build and it’s in the Processing state for more than 24 hours, there may be an issue with it. To resolve the issue, contact us.