Bitcoin Core – RPC batch calls suddenly stopped working.

I had this code that was working in less than a week. No changes at all to my PC or code and it just suddenly stopped working.

Plain (single) RPC calls work fine, but batching doesn’t.

You can rule this out as all firewalls are turned off and there is no virus protection. There is no change in port forwarding and I see both inbound and outbound traffic from my node. I restarted my PC and restarted Bitcoin Core (also with administrator privileges)

commands = (("getblockhash", height) for height in range(0, 100000))
            block_hashes = rpc_connection.batch_(commands)

I don’t understand why single RPC calls work fine but batches don’t.