10 bytes is not much.
Ok, understood: when sending with modem.endPacket(true) you are asking for confirmation, and if it does not come, it fails. But the packet is sent anyway, so you have to see it on the gateway even without confirmation. Are you using a real gateway or a single channel?
But in my experience, even if seems to fail, packets are received by the gateway, so you should see them in the log.
Just to sort out possible reasons for not receiving downlinks. Are you using ABP or OTAA, ADR, and eventually which SF? With The Things Network, there is a downlink issue when using high SF and ABP (it depends on RX2 frequency).
Regarding confirmation, downlinks are usually limited or expensive, so it is normally better to avoid confirmation for every message.
It is not the situation in which I found issues. Did you try to simulate a downlink? (the LoRaSendReceive example shows also downlinks when received). If confirmation is not received, likely there is some issue with downlinks. I do not know Orange offer; TTN limits the number of downlinks.