Android : Why busybox grep stop working?

From the first time I installed busybox pro version.apk it seems working.

Until then I run with or without "su" this command below:

busybox grep -ri "podnet" /

and then my terminal stop working. It is not hang or nor not responding either.

But i wonder why did the busybox grep seems not working, it doesn't give any output at all. The cursor seems stop at the beginning of the newline just like that.

Any clue?