In Jain tradition, Padmanabh is mentioned as the first Tirthankar of the next Chovisi / next Utsarpini in the Digambar tradition. In the Śvetambar tradition, the same future Tirthankar is often referred to as Mahapadma. ( jainknowledge.com)

A simple way to understand it is:

• Current Chovisi: starts with Rishabhdev and ends with Bhagwan Mahavir. ( jainknowledge.com)
• Next Chovisi: will begin in the next Utsarpini half-cycle, and its first Tirthankar is called Padmanabh in Digambar tradition. ( jainknowledge.com)

So, Padmanabh is not a Tirthankar of the present cycle; he belongs to the future cycle. ( jainknowledge.com)

If you want, I can also give you a simple Jain list of the next 24 Tirthankaras.