If the application sending the stream doesn't receive the CPA result as response, it is possible that not enough data was sent to IraCPA application. Each second represents 16KB of audio data. If AMD time limit set to 1.75 seconds, IraCPA can only respond once it gets 16KB x 1.75 = 28KB of data. Sending less than 28KB will be considered as incomplete data and no CPA result can be expected.
Check amdfiles directory if "log_voice" is "on". There may be recordings which are less than 28 KB around the time during which the response is not received. If IraCPA is on HA setup, check the amdfiles directory of all the servers.