iMac 2010 with GTX 780M Only Boots When USB Drive Is Plugged In

Hello,
I upgraded a 27-inch iMac (2010) with a GTX 780M (vBIOS mod) and attempted to run macOS Ventura. After installation, I am able to boot into the system. OpenCore then prompts me to install it on the internal drive, which completes successfully, including the root patches.

However, the system gets stuck on the boot screen when the USB installer is not connected. macOS only boots correctly when the USB drive is plugged in.

What would be the solution to this issue?