@Phil_Seeman I am using the Requests library for python.
headers = {'Authorization':'Bearer 0/XXXXXXXXXXXXXXXX}
r2 = requests.post('https://app.asana.com/api/1.0/tasks/'+ str(item), headers=headers, data = {"memberships": [{"project": 1131681448247237, "section": 1131889518013274}]})
str(item) is the tasks ID, I have also tried to hardcode a specific ID into the request endpoint and the result is the same. I used this topic to help me.