For clients using private IP addresses you need to enable 'NAT' (ip nat inside) on "ALL" the ingress RVI interface(s) of the client(s).
or much better would to use latest 7.4 version of Aruba switch, which provides option of 'ip nat outside', which can be applied on Just the 'egress' RVI interface (towards core switch).
NAT'ing is required for the 'reverse' traffic.
If this doesn't resolve your issue, then I have mis-understood your toplogy, in that case provide detailed topology diagram.