Bug with client possibly gameplay for ranked duo

I was told to post this here from a ranked play forum discussion submission. Me and my friend were both soft reset, I was plat 3 he was diamond 4 and wanted to play our placements together but we can't because it says that I have to "invite someone that's ranked from silver to platinum" which we can infer that it means I have gold mmr even tho I was play 3 last season. A little bit of back story I was gold 1 after decaying from plat 3 over a few months last year and got back into league after ranked rewards came out. I got back into play and played and duoed with my friend to play 3 in about 2 weeks because we played a lot and we worked well each other. This was done mainly through the new dynamic queue. So I have a gold border but I was in play 3 after the soft reset but my friend has a diamond border. I was just wondering maybe the system is determining duo queue partners by our borders? Thank you for taking the time to answer this!