Two changes to how US number plans ask for device details at checkout.
LinkUp Mobile
LinkUp plans need both your device IMEI and its EID, the same as the other US carriers we sell — that is what the carrier itself asks for. We had stopped asking for the EID on those plans, and because checkout still validated one, LinkUp orders could not be completed at all. Both fields are back and the plans are buyable again.
Moxee
Moxee lines activate on an eSIM we supply, so your QR code still arrives by email after payment and there is still no EID to enter. Checkout now asks for your phone's IMEI on these plans as well, which we keep on your order record.
Both numbers are on your phone: dial *#06#, or find them under Settings → General → About on iPhone, or Settings → About phone on Android.