MongoDB Stitch - 'Unable to load application data'

Recently my Angular App using Mongodb Stitch stop working, I got the following error

service cluster: server returned error on SASL authentication step: bad auth Authentication failed.

Some suggest that unlink/relink the Stitch App would solve the problem, but I don't have any idea how enter image description here

Then tried to add new Stitch App by clicking the Stitch Apps in left navigation, but it shows empty window, any ideas?

enter image description here