JSON-RPC error

Hi all, I submitted a ticket for the following issue they suggested I reach out to you guys.

I am getting:
JSON-RPC problem. Probably couldn't connect. Retrying in 1...
m 05:41:26|main Getting work package...
X 05:41:27|main Failed to submit hashrate.
X 05:41:27|main Dynamic exception type: class jsonrpc::JsonRpcException
std::exception::what: Exception -32603 : INTERNAL_ERROR: : {"id":999,"jsonrpc": "2.0","result": false,"error": "Invalid JSON request"}

When I try to run:

ethminer.exe --farm-recheck 200 -G -F eu1.ethermine.org:4444 -FS us1.ethermine.org:4444 -O 039a6c6fb5a5ec9d8b37cbcd538380dfcbbec430.Win10

Using servers us1, us2 doesn't change anything. My system has a GeForce GTX 750, with a mean hash rate of 966964 H/s

I was thinking this was a firewall issue, but apparently not.

Any suggestions are most appreciated!