Lech Poznan decided to sign Stjepan Loncar, who was expected to strengthen the team. Unfortunately, his time at the Poznan club turned out to be disastrous. After arriving at Lech in September 2024, expectations for the Bosnian were high, but his debut against Jagiellonia ended with just seven minutes on the pitch. In the following match against Śląsk Wrocław, he played even less, only six minutes. This was a sign of the troubles to come. In his third and final appearance for Lech Poznan, Loncar played in the Polish Cup against Resovia Rzeszów, where the team lost 0:1, and he left the field at halftime. After just a few months at Lech, the club decided to part ways with the player. In February 2025, Loncar moved to Croatian club Istra, where his form significantly improved. In his first season at the new club, he scored five goals and provided two assists, showing that returning to the Balkans was beneficial for him. Lech Poznan, despite the hopes placed in Loncar, had to look for other solutions on the pitch.