maybe they are to long?
but also even after you change the settings until the wallet route the payment for the first holding invoice, after the order is taken and you have to send another payment with the full final amount, the routing fail again, and no way to change any settings to get this working.
I don't see any other service failing for the phoenix wallet so far.
This suggests that they limit the number of HTLC in flight to 1. Really strict, but they are large and really spend much effort on security.
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