no vertical "aiming" line on plot when 3D view is off

picture illustrating the vertical line I am taking about:
https://drive.google.com/file/d/14KFtg8pBJpHXypIuC_CFi4bhmHGipjU8/view?usp=sharing
Please note that this line will disappear when 3D view is closed, which IMHO is not a desirable behavior.
This is also not the same as "Toggle Spike Lines" which are way thicker and the vertical spike line is not through whole height of a plot.

No source file or test is named. Reproduce the plot with 3D view enabled and then disabled, compare the aiming line with the Toggle Spike Lines behavior, and trace the plot-rendering entry point. Done means the vertical aiming line remains visible through the plot height when 3D view is off, without changing the thicker spike lines.

Written by the indexing model from the issue text.