Part of the theory behind maintaining a fixed percentage allocation of your portfolio to different asset classes, like stocks and bonds, is that when markets are volatile, you can increase returns by rebalancing. Unfortunately, there is no immediate return from rebalancing.
To show that rebalancing has created a profit, you need to take into account not just your most recent rebalancing trade, but also the last time you rebalanced in the other direction. If you do the calculation, it will show whether the second to last rebalancing trade produced a profit, but the most recent one won't show a profit until the next time you rebalance in the other direction.
This situation creates a problem of a delay from effort to reward. We're much better at doing things that give immediate gratification.