Checkout not working. No error message provided

[78-D]

What Happened?

When I tried to order two items from the elementary store, the "checkout" is not working and the page goes back to the state where I can only click "get shipping rates"

no error message or any other feedback provided

Steps to Reproduce

1. go to https://store.elementary.io
2. add items e.g., a mug and a cap
3. add shipping address in germany
4. add email
5. add phone number (BTW: here the intl formatting like +49 xxx xxx xxxx is NOT accepted)
6. click "get shipping rates"
7. select shipping rate
8. click "check out"
9. somethings fails and brings you back to point 6 (without hinting what went wrong)

Expected Behavior

should be able to buy items in the online store

OS Version

Other Linux

Software Version

Latest release (I have run all updates)

Log Output

no log,no error message, no warning

Hardware Info

No response

[btkostner]

API error:

(Printful.ApiError) Item 0: thread_colors option is missing or incorrect! Allowed values: #FFFFFF, #000000, #96A1A8, #A67843, #FFCC00, #E25C27, #CC3366, #CC3333, #660000, #333366, #005397, #3399FF, #6B5294, #01784E, #7BA35A