Gingejbee, there is not necessarily anything wrong with the words, "the group are missing."
"In British English, collective nouns MAY be correctly followed by either a singular or a plural verb." (My capitals)
The quote above is from Fowler's Modern English Usage, widely recognised as one of the ‘bibles' of what is admissible.
Example 1...
a. The jury retires later today to consider its verdict.
b. The jury retire later today to consider their verdict.
The word ‘jury' is definitely singular, as there is a plural form, ‘juries'...yet jury can have either a singular or plural verb-form and a singular or plural possessive form.
Example 2...
Someone may approach a bridge card-table and ask one of the players: "What's trumps?" The question he is obviously asking in his own head is: "Of the four suits in the pack, which individual one is the trump suit for this game?" (Clearly singular for him, hence the verb ‘is'.)
The player may well reply: "Clubs are." The answer he is obviously providing in his own head is: "All the cards in the pack which are club cards are trump cards." (Clearly plural for him, hence the verb ‘are'.)
Example 3...
It is perfectly acceptable to say either, "Manchester United are playing well at the moment" or "Manchester United is playing well at the moment."
It all depends on whether one sees the collective word under consideration as singular or plural in the particular circumstances, as suggested by the words, "in his own head" above.
Some collective words - collection, for example - would probably never have ‘are' as the associated verb but, for a multitude of others, it is quite clear that you are free to use either a singular or plural verb.