Sinusoidal voltage source not being sinusoidal in LTSpice
When needing high dynamic range outputs in .TRAN, the .opt plotwinsize=0 card should almost always be added to the schematic. That disables waveform compression which is, by default 300 points (you can check that by R-Click on the waveform window and select View &gt; Mark data points). What you have there is a mV ranged signal on top of V worth of DC.

The downside is (may be) that the .raw file will get larger, in which case the .save card can be used.

If that doesn't help, try what @jonk, and then @SpehroPefhany said, in that order.