LinkedIn Assets API: No AWS key returned when registering multi-part upload - linkedin

Question

I'm trying to upload a video > 200MB via https://api.linkedin.com/v2/assets. When registering a MULTIPART_UPLOAD I do not receive the "x-amz-server-side-encryption" or "x-amz-server-side-encryption-aws-kms-key-id" headers information anywhere in the response. I do get those when registering a SINGLE_REQUEST_UPLOAD and I'm able to successfully upload a video file < 200MB using that mechanism.
Example response for registering a multi-part upload:
{
"value": {
"uploadMechanism": {
"com.linkedin.digitalmedia.uploading.MultipartUpload": {
"metadata": "{METADATA}",
"partUploadRequests": [
{
"headers": {
"Content-Length": "5242880",
"Content-Type": "application/octet-stream"
},
"urlExpiresAt": 1547231882996,
"byteRange": {
"lastByte": 5242879,
"firstByte": 0
},
"url": "{AWS_UPLOAD_URL}"
},
{
"headers": {
"Content-Length": "5242880",
"Content-Type": "application/octet-stream"
},
"urlExpiresAt": 1547231882996,
"byteRange": {
"lastByte": 10485759,
"firstByte": 5242880
},
"url": "{AWS_UPLOAD_URL}"
},
{
"headers": {
"Content-Length": "3585789",
"Content-Type": "application/octet-stream"
},
"urlExpiresAt": 1547231883023,
"byteRange": {
"lastByte": 580302588,
"firstByte": 576716800
},
"url": "{AWS_UPLOAD_URL}"
}
]
}
},
"mediaArtifact": "urn:li:digitalmediaMediaArtifact:(urn:li:digitalmediaAsset:{ASSET_URN},urn:li:digitalmediaMediaArtifactClass:aws-userUploadedVideo)",
"asset": "urn:li:digitalmediaAsset:{ASSET_URN}"
}
}
I have tried to upload to those urls without the two headers and get a 403 Forbidden response saying I'm missing signed headers. The "x-amz-server-side-encryption" and "x-amz-server-side-encryption-aws-kms-key-id" should be returned in the register response right? If not, how do I make requests to aws without them?