Stuck at 10 no matter what I do which means only 20 cinders drop per boss instead of 60 plus from 25 man.
When a raid gets added as the timewalking raid for that expansion, it gets “updated” to being a flex raid. This means it no longer has the concept of 10 man / 25 man etc. It is scaled for as many people as you have - except if you have less than 10 it doesn’t go below 10. So yeah, this is how it works now, and is not a bug.
I have read (though not tested myself) that you can get cinders on both normal and heroic each week if you run it on both.
I recently ran Firelands for rep. I can confirm that you can run both Normal and Heroic in the same week and get drops in both.
Firelands still drops loot as if it were a 25-man even when it scales down.
Not cinders it doesn’t it’s 18 to 20 per boss instead of 60 plus