It's a new month and you don't see all of your categories from the previous month there. Below are some ways this could have happened.
When you click on the button to "Start Planning for ___“ for a new month, all of the budget items and planned amounts from the current month's budget will pull over into that new month's budget. If you clicked on this button early on (planned out future months way in advance) and then made changes to prior budgets after that, then those changes/updates will not automatically pull over into the new month (or future budget months).
This is one reason why we normally recommend that users wait until the end of the current month to hit that button to start planning the next month's budget.
If you click the "Reset Budget" button at the bottom of your budget now this will move all of your assigned transactions for the month into the “New” transactions queue as though they have not been assigned yet and it will pull over any budget items from the previous month that you do not have in the current month.
You may need to edit that planned amount for that month, but then moving forward it should copy over correctly into other budget months as long as they are not already planned.