If you are using the standard Mendix sandbox environment I would request a support call ( https://support.mendix.com/)
Because this seems like an underlying AWS platform error.
Regards,
Ronald
[EDIT]
I just noticed that you are using the Beta version. You can not deploy that one to the Sandbox yet. Only Mx7 versions work currently on the sandbox.
Thanks for the response Ronald, I will give that a try.