AFLplusplus: afl-fuzz instances don't import paths in parallel mode

I have single computer parallel fuzzing with 1 master and 2 slaves.

The relevant part of the shell script file used to launch afl-fuzz:

AFL_INST_LIBS=1 AFL_ENTRYPOINT=0xF25F1090 AFL_QEMU_PERSISTENT_GPR=1 AFL_QEMU_PERSISTENT_ADDR=0xF25F1090 AFL_QEMU_PERSISTENT_RET=0xF25F11E8 afl-fuzz $1 $2 -i in -o out -Q -m none -t 30000 -f "wtf_$2.bin" ./testbin  wtf_$2.bin

-M master or -S slaveX are passed as parameters to the script.

At this moment those instances have the following stats:

master: 4 cycles done, 3231 paths slave1: 960 cycles done, 3292 paths slave2: 772 cycles done, 3267 paths

All of the instances have 0 paths imported. Do you have an idea why they could not import paths?