Sounds like the modulation is going much further (off the scale) off of each side. The Sin wave is one extremity of the OscWav wavetable.
You need to centre the OscWavSelect origin, and then narrow any LFO modulation intensity accordingly.
Remember an LFO is bipolar, so setting the Osc1 Wav Select knob origin to the centre (64) will allow the bipolar LFO modulation to rock either side of this value, positively and negatively, so there is no bias.
Now lower the modulation intensity of the LFO until you can hear the modulation not going off the scale of each side, but still reaching the outer limit of the wavetable. I just tested it and an LFO intensity of 30 should suffice. I think 31 goes off the edge a touch.
Use a triangle LFO wave if you want a linear ping-pong sweep, as a sine wave will naturally languish at the extremities.
PS > And another thing! Will the Ti|3 have user customisable/importable wavetables?
A ribbon-controller or XY-Pad might be nice, too, please! Thanks!