When you collected the last panda, did you get a "new items for purchase in the secret shop" message? If not, you're missing one still.

you probably forgot at least one plushie. an easy way to check is once you completed all the pro goals, you will unlock solo tours, and in the character selection of solo tours there will be an item check box at the bottom right of the screen, such as the stat points with a check mark, if you have all the pandas it will appear there with a checkmark as well. if its not there, you did not collect them all. you may be a ways off from solo tours (no idea on your progress) but thats what i would do and disregard constable richard for the time being incase it is a glitch.