Tried to access EFI on Windows 10 side using the superuser link posted earlier (both methods), doesn't work either.
select disk x select partition y
Interesting that both 128mb relocation block or setting config.plist/RtVariables/CsrActiveConfig=0x67 seem to fix it.
If you could confirm (use old 96mb OsxAptioFixDrv-64.efi and CsrActiveConfig=0x67).
Why CsrActiveConfig=0x03 takes more memory... unknown.
I originally proposed 128mb (for 10.11). But others reported it working with 96mb, so Slice adopted the 96mb as it was a smaller change from 64mb.
Seems like it should now go to 128mb...