1. you are missing L3 assignment of your RVI
set vlans vlan-400 l3-interface vlan.400
2. Once you set that you will then have two routes to 10.0.0.0/24 since lo0 is overlapping with vlan-400
root@ex2200-c> show route protocol direct
inet.0: 6 destinations, 7 routes (6 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both
10.0.0.0/24 *[Direct/0] 00:08:17
> via vlan.400
[Direct/0] 00:00:03> via lo0.0
Change lo0 to use a /32 and, assuming your default gateway is set correctly on your NMS, you should be able to reach both.
root@ex2200-c> show route protocol direct
inet.0: 6 destinations, 6 routes (6 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both
10.0.0.0/24 *[Direct/0] 00:07:40
> via vlan.400
10.0.0.240/32 *[Direct/0] 00:00:24> via lo0.0