Sorry to hear about the issue. Premiere Pro can use Intel and NVIDIA GPU to process different things. The Mercury Playback Engine running on the dedicated GPU isn't used to process everything related to the GPU. The integrated GPU can be used for specific tasks such as encoding/decoding certain codecs and User Interface (UI) activity which can show up while monitoring the GPU usage.
Also, the System Compatibility Report suggests that your Intel Graphics driver is outdated. Please update to the latest driver from this link. If it doesn't help try following the steps mentioned in this article. Hope it helps.