Understanding the Issue with Dual Booting After OCLP Installation

It appears you've encountered an issue where, after a clean installation of macOS Ventura using OpenCore Legacy Patcher (OCLP) on your MacBook Pro 2015, you can still see the Windows partition, but it's not bootable. Let's explore what might be happening and how to address it.

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1. EFI Partition for Windows:

   • As mentioned in the comment, there's likely a separate EFI partition for Windows on your drive. When you install a new operating system, the EFI partition related to that OS gets updated or recreated. However, the EFI partition for the other OS (in this case, Windows) remains untouched.
   • This situation can lead to issues where the Windows boot loader is not recognized or is unable to initiate due to changes in the disk's partition scheme or boot configuration.

2. OpenCore on Separate Partition:

   • OCLP might have created its own EFI partition or utilized an existing one. If it’s on the same partition as the Windows bootloader, it might have overwritten or conflicted with the Windows boot files.

3. Steps to Resolve:

   • Check Partition Layout: Use a disk utility tool to check the partition layout of your drive. Identify the EFI partitions and their contents.
   • Recover Windows Bootloader: You might need to repair the Windows bootloader. This can typically be done using a Windows installation disk or recovery USB, and then using the repair options.
   • Configuring OpenCore for Dual Boot: Ensure that OpenCore is correctly configured for dual booting. This involves setting up the OpenCore EFI partition with the necessary files to boot both macOS and Windows.
   • Backup Before Modifications: Always back up important data before making changes to partitions or bootloaders.

4. Why Windows is Still Visible:

   • The Windows partition remains visible because the data partition where Windows is installed is still intact. However, the ability to boot into Windows depends on the EFI partition's boot files, which might be disrupted.

5. Further Troubleshooting:

   • If you’re not comfortable making these changes, or if the standard repair processes don’t work, seeking help from a professional or a dedicated tech forum might be advisable.
   • Documentation: Keep a record of the steps you take for troubleshooting. This can be helpful if you seek further assistance.

6. Future Precautions:

   • When dual-booting, especially with modifications like OCLP, it's crucial to understand how bootloaders interact and to carefully plan installations and updates to avoid such issues.

In summary, your situation likely involves a conflict or an overwrite of the EFI boot files for Windows due to the macOS Ventura installation and OCLP setup. Careful inspection and repair of the EFI partitions and boot files should help resolve the boot issue.