Hi,
Creating a new wallet and then configuring XMRig gives you:
xmrig exited, waiting to cooldown a bit
No valid configuration found. Exiting.
xmrig exited, waiting to cooldown a bit
No valid configuration found. Exiting.
xmrig exited, waiting to cooldown a bit
No valid configuration found. Exiting.
Using my old wallet that i created a few months back, is working on same rigs without any problem.
Editing any old wallet which is a couple of months old and enabling XMRig there, also works ok. So the problem is related to creating new wallets, and AFAIK it only breaks XMRig, not other miners.