When backup static route is configured with ospf, the FIB update might not work as expected.
As per jira - I95-59131, there is a race condition in OSPF code and the FIB update message (end of fib).
This issue will be fixed in following releases.
SSR-6.1.13-lts
SSR-6.2.8-lts
SSR-6.3.1-r1
SSR-6.3.3-r2
SSR-6.4.0