Career Tenure…how does it work?

I was a government employee for over 3 years and had tenure marked on my sf-50. Left the government and had to redo my probation. Now I am past probation but hr says I have to redo my three year period to get tenure again. Does that sound right? How does that affect me for rif? My rif date includes all my prior service. So am I stuck at career conditional until I have three years of service again?