Hello @tomc.pnnl ,
locally generated BGP routes have weight 32768 by default and this makes them preferred over the iBGP route coming from another neighbor.
To solve this my suggestion is to increase weight for the neighbor advertising the prefix to 40000
router bgp 1
neighbor <x> weight 40000
if you want to increase the weight only for a specific prefix you can use a route-map
ip prefix-list SOME permit 172.18.0.0/16
route-map RISE-WEIGHT permit 10
match address prefix SOME
set weight 40000
route-map RISE-WEIGHT permit 20
the last empty block allows to accept all other prefixes without change otherwise they are denied by implicit deny any
router bgp 1
neighbor <x> route-map RISE-WEIGHT in
Hope to help
Giuseppe