Presume we have a solver config like this:

<unionMoveSelector>
  <cacheType>STEP</cacheType>
  <changeMoveSelector>
    <fixedProbabilityWeight>2</fixedProbabilityWeight
  </changeMoveSelector>
  <swapMoveSelector>
    <fixedProbabilityWeight>1</fixedProbabilityWeight>
  </swapMoveSelector>
</unionMoveSelector>

If there are 300 changeMoves and 7000 swapMoves, you'd still expect that for every 3 moves you select, there's 2 changeMoves and 1 swapMoves, due to the fixedProbabilityWeight lines.

But that's not the case, it completely ignores that (so it should either fail fast on that or respect it), and gives you a 3/73 chance to select a change move and 70/73 chance to select a swap move.