Receiving a 400 error when trying to update the Site of a phone

I'm trying to change only the Site of a Phone using the PUT api/v2/telephony/providers/edges/phones/{phoneId} API. The request sent is as follows:

{
"name": "PhoneName",
"site": {
"id": "NewSiteID"
},
"phoneBaseSettings": {
"id": "phoneBaseID"
},
"lines": [
{
"name": "LineName",
"template": {
"id": "LineTemplateID"
},
"site": {
"id": "LineSiteID"
},
"lineBaseSettings": {
"id": "lineBaseSettingsID"
}
}
],
"webRtcUser": {
"id": "PhoneUser"
}
}

When I try to execute the request sending a UserID of a user who doesn't have a WebRTC phone assigned, the action is executed normally. I receive a code 200, and the information is changed in Genesys. However, when the UserID sent is the same as the one already linked to the WebRTC phone or any UserID that already has another WebRTC phone assigned, I receive the following error:

{
"message": "A web rtc phone has already been assigned to this user.",
"code": "bad.request",
"status": 400,
"contextId": "cdcd0a4e-eb19-4cca-a41b-89cfc50e4846",
"details": [
{
"errorCode": "ONLY_ONE_WEB_RTC_ASSIGNMENT_ALLOWED",
"fieldName": "webRtcUser"
}
],
"errors": []
}

Can someone help me with this issue since this information (WebRTCUser) will not be changed?