Hi Abbie2004,
Thank you for posting in the Community!
Leave balances appearing on pay slips would not reflect any leave taken if the pay run has not yet been finalised. If you are viewing a Draft Pay slip for a pay run that has not yet been finalised, this is working as normal. To view the correct balances, finalise the pay run and view the final pay slip.
I hope you find this helpful.
Best,
John Enrico