VLOOKUP not working as intended

I’m having trouble with VLOOKUP working incorrectly. I am using it to calculate how long my breaks should be based on how long my hours are.

In one row I can have:
Start – 07:00, Finish – 13:00, Break – 00:15 (Incorrect, it should be 00:30)

But in the second row I have:
Start – 08:00, Finish – 14:00, Break – 00:30 (Correct, for every 6 hours I work I receive an unpaid 30 minute break)

I am at a loss on how to fix this. Cell formatting is the same across all cells.

The problem is clearly shown on the spreadsheet itself.

That seems to have done it. Thank you!