Flex queue

Ok so, I'm challenger at flex atm and invited a diamond 2 player at flex to play. Normally this should have worked since challenger, as seen in the picture, can play with d5 and higher. But for some reason when we are in the same lobby it says the difference is too high for this queue.I then tried to see if it works with d1 at flex and it doesn't. Apparently i can only play with master+ atm but there isn't anything in patch notes to change how flex queue works.

So i decided to post here in case this is an undiscovered bug following the new patch.