Hello there @itsBarrex!
Since all the installation was performed on the P: drive, all related processes should use that very same drive. Just to make sure, search for “UnrealVersionSelector-Win64-Shipping.exe” in Engine\Binaries\Win64, and run it as an admin, this should register that location as main.
The specific project may require a re-mapping of the UE version being used, so right click on the myProject.uproject → switch unreal engine version → point it to the latest version.
If the issue persists, the other path left is a complete removal of all Epic software in your system, then installing from scratch:
- First, uninstall the engine, launcher, asset packs, etc
- Next, open the registry directory HKEY_CURRENT_USER\Software\Epic Games\Unreal Engine\Builds, and delete any build entries
- Finally, delete the folders %userprofile%\AppData\Local\UnrealEngine and %userprofile%\AppData\Local\UnrealHeaderTool
- After that, reinstall UE launcher on the P: drive