In the first case, you've specified every lot you've sold. You have sold any, so you didn't need to specify any.
In the second case, you haven't specified the shares you sold, so this investment isn't fully specified, and thus the un-specified lot markers can't be displayed. To change this, right mouse click on the investment, and choose "Investment Data / Specify Lots..." and specify which shares you sold when you sold those shares. Once you do this, your remaining purchased shares will have the un-specified lot markers displayed.