After checking more, the SKU-search is working when I type the whole SKU. I mean, if the SKU is abc123, I have to type abc123 and not stop at abc or something.
I purchased Table Rate Shipping Plus 2-3 weeks ago. I received the same email as shown above in this topic. I sent emails to both Mangohour and Paddle. No response from any of them yet! I contacted Paypal after a few days and got my money back.