'Shipping rate not found' when purchasing only FEDEX labels

HELP PLS! When I go to purchase a Fedex label, it keeps saying ‘Shipping rate not found’ even though it’s being shown on the list of labels to purchase. I’ve tried clearing cache, using a different browser, device, turning off wifi, etc. but it’s been about 4 months since I’ve been able to purchase a Fedex label which are a few dollars cheaper for each order. Unfortunately the Shopify specialist takes over 24hrs to respond and I can’t wait that long to send out an order. Any tips?