Can you share your SOQL query ?
Otherwise, verify the source settings are correctly configured in your copy activity.
If you are comfortable with editing the JSON code directly, review the JSON configuration for the copy activity.
If your problem still persists, you may need to open a ticket to the support :
{
"name": "SalesforceDataset",
"properties": {
"linkedServiceName": {
"referenceName": "SalesforceLinkedService",
"type": "LinkedServiceReference"
},
"type": "SalesforceObject",
"typeProperties": {
"query": "SELECT Id, Name FROM Account"
}
}
}