We just booked a return trip for the Nations League with EasyJet; two legs each way with the price inclusive of their DoHop transfer guarantee for the connections, but only three of the four flights appeared on confirmations. Missing one homeward leg.
EJ's "help" bots were useless. We eventually found an 0330 number to call (so probably paying for the pleasure), and after a while they gave us DoHop's number to call instead.
DoHop said the problem was that 3 flights were in £ and the one in €. They sent us an email with instructions on how to push the payment through, but we still got "There is a Problem". So back on the phone and they sent another email and told us to re-book the missing leg manually with EasyJet, and they say we will still have a transfer guarantee when we reply to DoHop's email with the booking ref. for their records.
Hopefully their IT folk sort this out for others.