Seems to me that your single-channel test gateway does not support downlinks:
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Your uplink (when using ABP) seems to be a confirmed uplink, which expects a downlink with an acknowledgment. You can see the 14 bytes downlink (blue downwards icon) in TTN Console, but apparently the node is not receiving it. LMIC is likely re-trying the uplink at some later time, but it’s then probably using a frequency or spreading factor that your single-channel test gateway is not listening to.
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OTAA needs a downlink for the OTAA Join Accept. Again, you seen it in TTN Console, but apparently the node is not receiving it.