Can't invite friends 1 tier away to ranked game

I finished Season 5 ranked Diamond 5, after ranked reset when I try to invite friends to a ranked game I can only invite players ranked Bronze-Gold. I was banned last August and lost ranked rewards. My guess is that my rank was completely removed so now I have default start for the season. This also means that I will be placed in gold at the start instead of platinum, which would be really annoying. Hopefully this isn't how it's supposed to work considering Riot never said this was going to be how it worked.