If you think foods are missing from your grocery list, double check that the grocery list is synced to include the date of the meal plan with missing foods. You can see the sync dates here:
If it does include the date of your meal plan, try resetting it with the same dates anyways - if you delete a food from the grocery list, it won't show up again until you reset the grocery list (or until the next week, when the weekly planner will automatically regenerate your plans and reset the grocery list to match).
If that's still not solving the problem, there could be a bug somewhere. Please let us know! You can reach us at firstname.lastname@example.org . We usually respond within a day, and I make an effort to fix grocery list issues as soon as possible.