Wrong result when using :minimize on product of negative vars

[yuhan0]

I'm trying to use Loco to minimize the sum of squared errors in a constraint problem, however it seems that the solver is giving the wrong result when the variable ranges go into the negative numbers:

(solutions
  [($in :e -5 5)]
  :minimize ($* :e :e))
;; => ({:e 5})

Oddly enough, creating a temporary variable solves the issue in this case, but not in a larger model involving multiple squared vars.

(solutions
  [($in :e -5 5)
   ($in :sse -1000 1000 :bounded)
   ($= :sse ($* :e :e))]
  :minimize :sse)
;; => ({:e 0, :sse 0})

Am I doing something wrong here? The docstring for $* says

One of the arguments can be a number greater than or equal to -1.

which is confusing as to whether it handles both arguments being negative.