Hi,
Do you see interface routes in inet.0 now?
show route table inet.0 protocol direct
The static default route config should still be present:
set routing-options static route 0.0.0.0/0 next-hop 1.1.1.6
Then the default route would be present in inet.0.
rib-group is a way to exchange routes between different routing tables/instances.
https://kb.juniper.net/InfoCenter/index?page=content&id=kb16133
Cheers,
Ashvin