Hi Kara--
That's an unfortunate hassle.
Before you call USCB Intergovernmental Affairs, or whoever, you should check to see whether this tribal community is included or missing from the 2020 Census. That will tell you whether this problem is simple to solve, or not simple.
You can find the 2020 Census's table P1: Population, listing all American Indian + Alaska Native Areas , here https://data.census.gov/cedsci/table?q=p1&g=0100000US%242500000&tid=DECENNIALPL2020.P1&tp=true
Good luck,
Todd Graham
Metropolitan Council of the Twin Cities