Calling Telos' eosio.msig::approve() is not possible, because it needs an argument called "proposal_hash".
The problem is two fold:
1) proposal_hash is optional, and approve() should be able to be called without it
2) checksum256$ is not supported, most probably because of the new ABI 1.1, like this issue: https://github.com/EOSIO/eosjs/issues/284
Calling Telos' eosio.msig::approve() is not possible, because it needs an argument called "proposal_hash".
The problem is two fold: 1) proposal_hash is optional, and approve() should be able to be called without it 2) checksum256$ is not supported, most probably because of the new ABI 1.1, like this issue: https://github.com/EOSIO/eosjs/issues/284