usb serial android packet loss

Question

I am using com.github.mik3y:usb-serial-for-android.

Only some packets reach correctly, some packets lose their length. Sometimes I get a full packet, but usually the response is truncated. And the very first package is correct.

 private val readerReceiver = Runnable {
        while (!_needStopThread) {
            port.write("scn20 500000000 1500000000 5000000 200 20 10700000 8500 8\\r\\n".toByteArray(),200)
            var data = ByteArray(4096)
            val len = port.read(data, 200)
            data = data.copyOf(len)
            if  (data.isNotEmpty()) {
                callBack(String(data, 0, len))
            }
        }
        _needStopThread = false
    }

I tried using serial without a library, it didn't help. I tried to collect packages into one, but the essence does not change, it is part of the package that is cut off.