Paycheck hours are different from hours worked...

Hi everyone.

I'm here on behalf of my girlfriend, who's a barista at Starbucks. She was worried this morning because her paycheck seemed short even though she's been working a lot, so she went back through the past 7 pay periods, and it looks like 3 of those periods she's been shorted by over 6 hours (6.7, 6.45, and 6.6).

She said that she went through the physical book where they write their time in, and she checked online, she accounted for the days she switched shifts, she also made sure that the hours were accurate for the pay period.

She also told me that another barista checked her records and was also missing about 8 hours from this most recent pay period.

Before I jump to any conclusions and tell her to call corporate or the DM, can anyone here think of why people would be missing hours? I don't want to start a witch hunt and I told her to start going through her records before April, but this is almost $200 she's missing over three checks.

I'd appreciate any help anyone can offer!