Hyperledger - peer unable to instantiate chaincode after joining channel - hyperledger-fabric

Question

I currently have a running Kafka-based hyperledger running on docker.
The full container list is as such:
2x orderer
2x peer
1x certificate-authority
3x zookeeper
4x kafka nodes
1x cli tools
I have sucessfully created a channel using cli by the following command
docker exec -e "CORE_PEER_LOCALMSPID=Org1MSP" -e "CORE_PEER_MSPCONFIGPATH=/etc/hyperledger/fabric/msp/users/Admin#company/msp" peer0.company peer channel create -o orderer0.company:7050 -c messagebus -f /etc/hyperledger/configtx/channel.tx
docker exec -e "CORE_PEER_LOCALMSPID=Org1MSP" -e "CORE_PEER_MSPCONFIGPATH=/etc/hyperledger/fabric/msp/users/Admin#company/msp" peer0.company peer channel join -b messagebus.block
I can see the peer is joined using the following command:
docker exec cli peer channel list
2019-01-07 16:54:41.784 UTC [channelCmd] InitCmdFactory -> INFO 003 Endorser and orderer connections initialized
Channels peers has joined:
messagebus
I then want to init and instantiate my chaincode as such
#install the chaincode
docker exec -e "CORE_PEER_LOCALMSPID=Org1MSP" -e "CORE_PEER_MSPCONFIGPATH=/opt/gopath/src/github.com/hyperledger/fabric/peer/crypto/peerOrganizations/company/users/Admin#company/msp" cli peer chaincode install -n testnet -v 1.0 -p "$CC_SRC_PATH" -l "$LANGUAGE"
2019-01-07 16:46:23.154 UTC [chaincodeCmd] checkChaincodeCmdParams -> INFO 003 Using default escc
2019-01-07 16:46:23.154 UTC [chaincodeCmd] checkChaincodeCmdParams -> INFO 004 Using default vscc
2019-01-07 16:46:23.615 UTC [chaincodeCmd] install -> INFO 005 Installed remotely response:<status:200 payload:"OK" >
#instantiate the chaincode
docker exec -e "CORE_PEER_LOCALMSPID=Org1MSP" -e "CORE_PEER_MSPCONFIGPATH=/opt/gopath/src/github.com/hyperledger/fabric/peer/crypto/peerOrganizations/company/users/Admin#company/msp" cli peer chaincode instantiate -o orderer0.company:7050 -C messagebus -n testnet -l "$LANGUAGE" -v 1.0 -c '{"Args":[""]}' -P "OR ('Org1MSP.member','Org2MSP.member')"
2019-01-07 16:46:24.210 UTC [chaincodeCmd] checkChaincodeCmdParams -> INFO 003 Using default escc
2019-01-07 16:46:24.210 UTC [chaincodeCmd] checkChaincodeCmdParams -> INFO 004 Using default vscc
Error: error endorsing chaincode: rpc error: code = Unknown desc = access denied: channel [messagebus] creator org [Org1MSP]
As the final line shows, the access is denied to the channel.
I am also unable to join a Java SDK client to the channel and receive similar access denied errors.
I see the following logs in the peer0 container:
2019-01-07 16:46:23.611 UTC [endorser] callChaincode -> INFO 0f1 [][bfb2e2d4] Entry chaincode: name:"lscc"
2019-01-07 16:46:23.614 UTC [lscc] executeInstall -> INFO 0f2 Installed Chaincode [gmex] Version [1.0] to peer
2019-01-07 16:46:23.614 UTC [endorser] callChaincode -> INFO 0f3 [][bfb2e2d4] Exit chaincode: name:"lscc" (2ms)
2019-01-07 16:46:23.614 UTC [comm.grpc.server] 1 -> INFO 0f4 unary call completed {"grpc.start_time": "2019-01-07T16:46:23.61Z", "grpc.service": "protos.Endorser", "grpc.method": "ProcessProposal", "grpc.peer_address": "XXX.XXX.X.XXX:123", "grpc.code": "OK", "grpc.call_duration": "3.771114ms"}
2019-01-07 16:46:24.214 UTC [protoutils] ValidateProposalMessage -> WARN 0f5 channel [messagebus]: MSP error: the supplied identity is not valid: x509: certificate signed by unknown authority (possibly because of "x509: ECDSA verification failure" while trying to verify candidate authority certificate "ca.company")
this leads me to believe the peer is not correctly setup... however it is able to create the channel successfully.
Any pointers would be appreciated