Ranked Queue Issues

Hello folks and Riot employees!

I'm currently trying to play my placement matches with my friends. However, I can't join a group with my unranked friends (who were silver ranked players last season) or join one of their groups. However, I can accept an invite from my other friend who has never played ranked. I was Gold 4 ranked at the end of the last season.

I would really like to play group ranked this season, but right now I'm stuck playing normals.

Is this a known bug? Is there anything I can do, apart from solo queuing?

Please get back to me ASAP :D