I have just lost my eligibility for premium delivery because I cancelled 1 order so my stats are 0.7% cancellation rate. I think it is harsh to have the same restrictions for handmade sellers as it is sometimes impossible to not cancel an order if the customer has made an error with customisation info and doesn’t respond to messages. I guess there is nothing I can do but wait for a month for it to drop off my stats?
I presume you have contacted Handmade support.
There is a lot of Seller Central that does not work for Handmade users. The best thing that we can do is report all issues so they can work on ways to fix issues.
David