LTSpice Transconductance Amplifier Simulation
Creating the current source with a table starting at 0V 0A probably clips your swing into the necessary negative direction, thus distorting the waveform and messing up the frequency response plot.

Giving it a wider range (-10V 1A, 10V 1A) gives it more headroom, but it could be clipping there too.

It might make more sense to use a BI source and simply set the current to a formula depending on the voltage of your node, this will not cause any clipping. I recommend though to label the net, as the n### automated node names can change.