P45 not showing my PAYE deduction

Hi there, As I was doing my tax return, I noticed that, for one of my previous employments, my P45 is not showing the PAYE Tax I got deducted from each of my payslips. I checked my PAYE income tax review on my HMRC page, and same story there- it looks like I have not paid taxes. For reference my tax code was 1257L. Why is that so? or is it a mistake? And eventually who I need to contact to sort it out? I do not want to pay double taxes at the end of the year, if it is a mistake. Thank you for the help in advance!

Hi,
For help with your query, you will need to contact our Income Tax team for advice.
Income Tax: general enquiries
Thank you.