Did u try 2019-02 version? It is available in the link I mentioned earlier. That one worked for me.
Nope. However I redid everything from scratch and used Adobe Acrobat Trial Version and uploaded. it worked with the latest form.
I would suggest if nothing helps then the best thing todo is start a new application then fillout IMM 1294 (the latest version), validate (make sure the extra page with the barcodes comes up) and upload within 10 mins (or as soon as possible).