Make sure that CsrActiveConfig is set to 0x67 on your config.plist.
Code:
<key>RtVariables</key>
<dict>
<key>BooterConfig</key>
<string>0x28</string>
<key>CsrActiveConfig</key>
<string>0x67</string>
</dict>
After adding above entry, try booting with OsxAptioFixDrv-64.efi & OsxAptioFix2Drv-64.efi (do not add both drivers at the same time)
If above drivers are still making same issue, then boot with attached OsxAptioFix2Drv-free2000.efi driver.