If you were hired externally, your vacation service date may not match your interpretation of your offer. It isn't visible in Workday, so you won't notice a discrepancy unless you ask.
To check, submit an HR ticket and ask them to look up your vacation service date and how it was calculated. Then compare it to what your offer letter or recruiter said about crediting prior experience.
The vacation policy was updated on April 1 this year to better align the offer language with the years credited, so if you were hired before that date, it's worth confirming which version of the policy was applied to you.