Glitched out key/no key

I cant find the key for the red shed in the police cars its like glitched out the key says its in my inventory but i dont see it and i need that key to finish that and move onto the next island, and its prompting me to “find a means to unlock the storage” i dont rewlly understand

Which mission are you talking about?
And btw, dots and paragraphs are really helpful.