best response confirmed by Ivan Palikuca (Occasional Contributor)

@Ivan Palikuca 


I have tested the case, both cases are working fine in my end. Actually you have to replace the {itemId} by <sub folder id> and you should not include the sub folder name (General) in graph url.


For example :{groupId}/drive/items/{folder_Id}/invite{groupId}/drive/items/{sub_folder_Id}/invite


You should not provide like below URL :{groupId}/drive/items/General/{sub_folder_Id}/invite