Why would a girl act like she doesn’t know me while she’s at work?

but we do know each other , i meet her last summer at this bar and even bought her and her girlfriend a shot , we've talked and definitely know each other

i'm used to experiencing this from the other way , usually the girl ignores me outside of her work , is ok with talking to me at work then ignores me when i see her somewhere else. not used to girl ignoring me when at work

Why would a girl act like she doesn’t know me while she’s at work?
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