Transmit status results in MAC ACK Failure in XBee XB8X

I’m using two XBee XB8X modules, API mode. I periodically check Extended Transmit Status - 0x8B for answer 0x25 (no route found). I often get back MAC ACK Failure answer, but even if connection is good. After 0x01 status (MAC ACK Failure) upcoming status is OK.
Please why I get MAC ACK failure ?

thank you for help

You are probably trying to transmit to often causing data collisions which is causing the ACK failure. The random back off and retry is what is getting thru.