DD 4200 with Veeam (Mtree issue)

HI Experts, We are trying to integrate Veeam with DD4200 . We have created a new Mtree/Storage unit under DD boost user for Veeam at DD of around 800GB . However we we add the DD and select the new Mtree as repository at Veeam we find the MTree size as 13GB only I have seen in the DD the soft limit of Mtree is 800GB and Hard limit is 1000GB but strangely i find 13GB as repository . DD boost 3.1 DD OS 6.0 Veeam 9.5 update4