The change owner functionality has been pretty bad in 8.x. I think they fixed it at one point, then maybe broke it again (my experience at least)
Also, I thought that I responded here with how to find the machines/tags but I'm not seeing it. Probably just losing my mind. So if I'm repeating myself here, I apologize.
Endpoint: /relocation/api/wo/query-unmanaged-machine
Payload:
{
"planLink": "/relocation/onboarding/plan/<plan id>",
"expandFields": [
"name",
"tagLinks"
],
"optionExcludePlanMachines": true,
"filters": [
{
"field": "NAME",
"values": [
"MyServer"
]
}
]
}
Response:
{
"page": {
"documentLinks": [
"/resources/compute/<1st compute id>",
"/resources/compute/<2nd compute id>",
"/resources/compute/<3rd compute id>",
"/resources/compute/<4th compute id>"
],
"documents": {
"/resources/compute/<1st compute id>": {
"name": "MyServer10",
"tagLinks": [
"/resources/tags/<some tag id>",
"/resources/tags/<some tag id>",
"/resources/tags/<some tag id>"
]
},
"/resources/compute/<2nd compute id>": {
"name": "MyServer17",
"tagLinks": [
"/resources/tags/<some tag id>",
"/resources/tags/<some tag id>"
]
},
"/resources/compute/<3rd compute id>": {
"name": "MyServer23",
"tagLinks": [
"/resources/tags/<some tag id>",
"/resources/tags/<some tag id>"
]
},
"/resources/compute/<4th compute id>": {
"name": "MyServer25",
"tagLinks": [
"/resources/tags/<some tag id>",
"/resources/tags/<some tag id>",
"/resources/tags/<some tag id>"
]
}
},
"documentCount": 4,
"queryTimeMicros": 170996,
"documentVersion": 0,
"documentUpdateTimeMicros": 0,
"documentExpirationTimeMicros": 0,
"documentOwner": "<some owner id>
},
"totalCount": 4
}
That endpoint mimics the Add Machines tab on your plan. The response will have a documentLinks array and documents dictionary. The links in the array are the keys for the object. So you can look through the array, and then access the id, tags, name for each machine. And those are the fields you need to when adding resources to the plan.