illustrator newest version 2020 in use:
it has issues in reverting the latest action. the one before the latest and all the previous are reverted while that last 1 stays the same.

lets say

1- line modification towards left
2- line resized
3- point of line modified from point A towards B

when pressing cmd+z only the actions nr 2 and nr1 are rverted. the position of the line in the nr3 doesnt go from B back to A. stays in B..