Hey!
my system: 5700 XT, 3x6700 XT, 6900 XT, + 6600 XT.
Before installing 6600 XT, the system worked stably on a 5.7c miner with drivers 21.3.1. -CLКernel 1. Good stable hashrate, 0 stale and invalid shares.
After adding the 6600 XT to the system, I had to install the latest drivers. With them 5.7 and 5.8b, the miner does not work in -CLKernel 1.
2 out of 6 video cards issue
Failed to compile program: clBuildProgram (-11)
Unable to prepare kernels: clCreateKernel (-46).
If I write -CLКernel 0, then all cards work, but the hashrate is slightly lower and 0-4% stale shares appear.
Are you on windows 10? Use DDU to remove all drivers and try again, install the drivers with the first card connected them turn it off and connect the other cards, I believe windows 10 will just identify the other GPUs and use the same driver installed which will work fine for those GPUs. I'm on 21.8.2 and working just fine with 5.8b.