How to call out my operators who are not working efficiently as a supervisor?

so there are a lot of individuals at work who are not working at full capacity let alone 50% capacity. As an logistics/ops supervisor, whenever i request for something to be done, they give some excuse saying that they have to do a “live load”. However, when I go do my walk around to look at other things, I do not see him back where he was and when i call him out the guy says “i went out to get some fresh air”.

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He then exploded at me saying he will finally do what i asked him to do an hour ago. Checking into the Management system, I saw that he took a break for 4.5 hours during the 8 hour period. How would you approach this conversation with him telling him that he’s taking WAYYY too long of a break ?

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additionally, as the supervisor, they keep complaining about how the other shift left them bad and in this mentality, they just do not want to do what theyre supposed to do because it was supposed to be done “before them” however, when i see them having a break for more than 4,5 hours im like “really?”

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please advise.