MEMORY UTIL shows "0" when reported per namespace

[andrey-parkhomets]

-> % kube-capacity  --util -n kube-system
NODE                                 CPU REQUESTS   CPU LIMITS      CPU UTIL    MEMORY REQUESTS   MEMORY LIMITS    MEMORY UTIL
*                                    20122m (8%)    49212m (20%)    0m (0%)     14718Mi (1%)      445160Mi (53%)   0Mi (0%)
aks-d4userpool-38467870-vmss000000   310m (8%)      500m (12%)      9m (0%)     220Mi (1%)        7162Mi (52%)     155Mi (1%)
aks-d4userpool-38467870-vmss000002   310m (8%)      500m (12%)      12m (0%)    220Mi (1%)        7162Mi (52%)     155Mi (1%)