switch signer in in-person signing

Hi I capture the traffic when switch signer in the signer dropdown list. I found that it actually sends a request something like: https://tst.esl.cibc.com/packages/Q85UFAY_Wf9jYW3mehuSbwFKzbs=/switch?from=joan1.river1%40email.com&to=joan2.river2%40email.com&hasSwitched=true My test case is we have 2 signers to signer: signer1 and signer 2 1) create a token for signer1 to signing 2) when signer1 completes the signing, select signer2 in the in person dropdown to start signing at this step, I send the request to switch signer (similar one like: https://tst.esl.cibc.com/packages/Q85UFAY_Wf9jYW3mehuSbwFKzbs=/switch?from=joan1.river1%40email.com&to=joan2.river2%40email.com&hasSwitched=true ) after this request, it seems signer2 session is still not open. how to start the session for signer2? Anything I am missing here? Thanks, Cindy