The Sphinx - Riddle #4 Error Can't Complete

I cannot complete The Sphinx - Riddle #4 Challenge. Every time I click on 'Play Solo' I get an error message that says "Error - Our Servers cannot process your request at this time, please try again later." I have completed every other The Sphinx challenge except this one. Changing my lineup does not work, auto-generating a brand-new lineup doesn't help. It kicks me out of Ultimate Team any time I try to play this #4 challenge. I can start and play all other The Sphinx challenges with the same lineup. The #4 is broken for me no matter what I try.