Question regarding to LTspice diode simulation :
Spice follows the passive sign convention: the positive current direction through a current or voltage source is from the positive node to the negative node.
Hence the negative sign.

You might find a resistor is sometimes also showing an unexpected sign. Probably Bonnevie is pointing that out.
Just rotate the resistor 180 degrees, or, download a resistor symbol with current arrow from ltwiki.org