ah, after lots of digging I finally found this article.
Child pages – 404 error/page not found – Ultimate Member
I did the same thing, after rolling back to Woocommerce version 3.2.6 the orders page starting working correctly. I have a sneaky suspicion it might be related to an ajax request. I have a test environment setup and I’m going to disabling plugins to see if I can isolate the cause.
