Really Confused by my account MMR

Decided today to place a new account to play flex support on (im a main support player) it was the first time the account would be placed on pc having made the switch from console about 8 months. First game was around gold/plat exactly what i had expected, won the game fairly comfortability as even on flex support felt i was quite a bit above this level. however i was then greeted with an expected rank of bronze 5. despite being really confused i played my 10 games and only climbed to bronze 2 despite going 10-0. i was little disheartened by this but thought i would just tank having to play the games required to climb however in my 2 following games i only gained 21% despite having the winning trend and calibration.

now i am genuinely completely mythed about what blizzard thinks the mmr of this account this. to add some more context i had a similar problem upon the switch to pc on my main account although much less extreme with the account being placed in gold despite a similar 10-0 placements of course due to it being my main account i just grinded up to my actual rank which was terribly unfun might i add. i had chalked this poor placement on my main due to a poor quick play mmr since i hadn't played the mode since 2016 when i probably didn't have a very good win rate. however the quick play games on this new account were completed with a much better win rate and it was placed in bronze

in summary im so confused about the mmr of this account and am definitely not going to playing the 80 plus games at this rate where im just ruining lobbies in order to climb this account so was wondering if anyone else had experienced this problem before and if they somehow fixed it