XBee 865 Async Pin Sleep not working !

We recently replaced XBee ZB RF Modules(ZigBee) with XBee 865/868 (India, DigiMesh) into our sensor designs. Our sensors used pin sleep method in transparent mode in the following manner :
Pin Wake (Sleep_RQ assert low) —> Wait Wake Up Indication (On/Sleep) —> Transmit UART —> Pin Sleep (Sleep_RQ assert high)

This process worked fine with XBee ZB however this doesn’t seem to work properly with XBee 865/868 DigiMesh we have configured the XBee properly with Async Sleep mode.

Could you please help us out with this issue?