Assuming VP versions later than VP16 have the same setting there is a "Quickfade Audio Edits" parameter in the 'Options' menu. I do not think Vegas has a 'zero crossing' audio parameter setting like Sound Forge with can eliminate some glitches. Disabling 'Quantize to frames' can often help fixing abrupt audio cuts. Just enable 'Ignore Grouping/, so the video (or other events in the group) do not change with it,.