End-Device does not receive downlink

So am using LMIC library and I have a prebuilt lite gateway which is integerated with chirpstack.
I am able to send both uplinks and data to the server, but I can not receive a downlink on my end-device.
Although I send both “confirmed” and “unconfirmed” downlinks but still no effect. I guess, the reason for that is the ack which is always set as false in the downlink, how can I change it? also if this is not the case, please refer to the following thread which illustrates my problem in a nutshell, as I already talked with the LMIC library creator and he mentioned that the problem is on the server’s side.

I guess this was solved, looking at the latest message in the above GitHub issue:

Yes, now it is working perfectly, and am printing received ack. Thank you for your patience and time