Hi,
I am also receiving the same issue regarding flex and getting the same error as above however I have tried on different browsers, devices and networks and getting the same issue so not able to add any of my subscriptions to flex
Certainly I am getting the same error attached on the screenshot below and getting this on different browsers, devices and internet connections
 
Hi AuchCal,
Thank you for reaching out to us in our community and welcome, sorry to see you were also facing an error, are you still facing the same issue, what was it you were trying to do when the error popped up?
Regards
Paul.
