Depending on how strict your settings are, the weekly meal generator can miss macronutrient targets. This is because the weekly generator places emphasis on trying to keep the grocery list manageable, only chooses from recipes that can be made as a single serving (unless it's being used for leftovers, or you're making the meal for a large number of people), and ensures there is variety between days.
Recurring foods can help dramatically. Adding some "often" or "always" recurring foods that you enjoy eating that also hit your macro targets well makes it much easier for the generator to figure out the rest of your plan. For example, if you're going for a high protein diet try adding a recurring protein shake or bar. Check out this article for more about recurring foods.
Try loosening some of your constraints. The following settings have a significant impact on how many foods the planner has to work with:
Try the single day generator instead of the weekly one. If you click the "Generate" button on a single day's meal plan, or regenerate individual meals/foods (as opposed to using the "Regenerate entire week..." button), the generator is much more likely to hit exact macro targets. This is because the in-browser generator places less emphasis on reusing ingredients from day to day, and much more on meeting the nutrition goals. If you can, look for the foods that are throwing the targets off the most, and regenerate those foods/meals specifically.
Of course, this isn't an ideal solution because it takes time to go through your meal plans and regenerate things if the generator is consistently missing. The root of this problem is when we don't have enough recipes to fit your exact preferences. The more strict your preferences, the fewer recipes the our have to work with and try to make meals that meets your nutrition targets. So if you select that you want a vegan diet, want lots of protein, and can't cook for any meal, the generator probably won't hit those targets.
That's a bit of an extreme example, and you might be experiencing this problem with more relaxed constraints. Even if we have a few dozen recipes that meet your preferences (maybe you have less than 5 minutes available time and a strict diet), we might use up the best ones in a few days of your meal plans, and then not have any good foods the next few days due to how the weekly planner attempts to add variety to your plans.