RF24Mesh master-base node communication delay
The nRF24L01 "ACK_PAYLOAD" feature allows for two-way data transfer in a single radio transaction.  This is more complicated to set up but plenty of tutorials can be found online, on arduino stackexchange and of course another very helpful source is the nRF24L01 data sheet.  This should solve your problem by ensuring the master/slave radio messages are sent in the same, rather than independent, radio transactions.