Depended dropdown menu's not working with Flask authentication

I am using this GitHub repository to create a multi-user authenticated app.

Everything seems to work fine individually, and I can get individual graphs working but when I have more than one dropdown menu the second dependent menu will not populate. Originally I thought it might be my own code but I then tested t with this code and I had the same issue.

It actually appears no dropdown example will work, even the basic dropdown example.

Any help or a workaround would be greatly appreciated