In Lightning Winter'17 Org, with OpenCti API 38 and Integration API 38, when I call from the developer console the 

    sforce.opencti.saveLog({Value:{entityApiName:'Task',Id:'00Txxxxxxxxxxxx',WhatId:'001xxxxxxxxxxxx'}});

the object Task with the Id 00Txxxxxxxxxxxx WhatId is updated correctly. The callback response is success and it returns an Id, indicating the entity with that Id was correctly updated and the WhatId is correctly assigned.

When I call the

    sforce.opencti.saveLog({Value:{entityApiName:'Task',Id:'00Txxxxxxxxxxxx',WhoId:'003xxxxxxxxxxxx'}});

I receive the same answer with success result and Id, but the WhoId is never updated.

Both calls have been tested with and without entityApiName, with the same result: WhatId is updated, WhoId is not.

Can anybody throw some light on this issue, please? Why WhoId is not updated when calling the sforce.opencti.saveLog and receiving a right execution response?