Downlink messages not being sent or received?

Hi! I’m currently trying to send unconfirmed downlink messages to a class A device using OTAA, but unsure whether the gateway isn’t sending them, or the device isn’t receiving them.

Gateway: RAK2245 on a Raspberry Pi 3B with Gateway OS
Device: Heltec WiFi LoRa (V2) using this library:

Gateway bridge logs:
level=info msg=“backend/concentratord: uplink event received” uplink_id=2f2feeca-e8af-437e-b9f9-f106d904a0f9

level=info msg=“integration/mqtt: publishing event” event=up qos=0 topic=devices/b827ebfffecadf86/messages/events/up uplink_id=2f2feeca-e8af-437e-b9f9-f106d904a0f9

level=info msg=“integration/mqtt: downlink frame received” downlink_id=746b39b7-60ad-45c4-a28f-bbb5ea10804b gateway_id=b827ebfffecadf86

level=info msg=“backend/concentratord: forwarding downlink command” downlink_id=746b39b7-60ad-45c4-a28f-bbb5ea10804b

level=info msg=“integration/mqtt: publishing event” downlink_id=746b39b7-60ad-45c4-a28f-bbb5ea10804b event=ack qos=0 topic=devices/b827ebfffecadf86/messages/events/ack

Concentratord logs
Frame received, uplink_id: b7fbcd00-b317-46e7-aa5f-99d96eb0841a, count_us: 2637737131, freq: 868500000, bw: 125000, mod: LoRa, dr: SF7

Enqueueing timestamped packet, downlink_id: eb8ee67c-630d-4309-8a27-11102c6b7d10, counter_us: 2638737131, current_counter_us: 2638154925

Scheduled packet for TX, downlink_id: eb8ee67c-630d-4309-8a27-11102c6b7d10, count_us: 2638737131, freq: 868500000, bw: 125000, mod: LoRa, dr: SF7

Do these logs mean that a downlink was sent? It seems so, but the logs contain the same messages when no downlink was queued. I am receiving a TxAck message, with an empty tags field (the message is not empty). The concentratord logs also contain messages saying “GPS time reference is not valid” in case that’s related to this issue.