PTT still ON after RX is over

[UB3AGF]

I have repeater based on a PI-STAR + MMDVM (BI7JTA version 2) + 2x Moto GM340 for retranslate DMR calls.
So it's works fine in a duplex mode, but after i finish call TX GM340 is translate silence about 3 seconds.
It's looks like when i make a DMR call MMDVM opens PTT and TX all voice traffic, after RX is finished PTT led still ON and repeater translate silence about 3 seconds, it doens't metter about call time - silence tail always = 3 seconds after that.
I think there is some parameters in a PI-STAR or MMDVM params that setup somekind of calls tail.
How i can turn off this tail ?
Thanks.