J-Link RTT "SEGGER_RTT_MODE_BLOCK_IF_FIFO_FULL" is not blocking the code as expected.

I'm using the following command to read channel 1:

fifoFile="/tmp/rtt1Fifo"


mkfifo $fifoFile


JLinkRTTLogger -Device -AT32F435CMU7 -if swd -Speed 5000 -RTTChannel 1 $fifoFile

When JLinkRTTLogger connects, the code starts executing immediately, but "Data written" in JLinkRTTLogger doesn't start counting. The code only blocks when JLinkRTTLogger disconnects.