I have similar problem with setting in "mixed" rig, which contains old R9 380 cards and a pair of RX480. Sometimes first setting applies to every card. Could fix it using OverdriveNTool only and skipping setting via miner.
You need to disable "AMD Crossfire" from Radeon Settings: go to Gaming -> Global Settings -> Global Graphics and you find here the option
It is disabled. Please do not think I am so new in rigs.
Moreover, I never seen when Radeon drivers enable crossfire for mixed cards automatically. Yes, if you install a pair of identical cards, driver will enable crossfire by default but never in my case.
And when crossfire enabled, it is easily reconizable in Claymore's monitor - paired cards will show equal temperature and fan speed.
As well as I am talking about mixed rig only, 470-480 rigs do not have the problem described above and the problem occured only after moving to "blockchain driver" and Claymore 9.8.