I don't see anything wrong with your 0.7.0 EFI, assuming the BlueGrey theme is in Resources/Image/chris1111/BlueGrey as you have it in PickerVariant.
I don't know what build number you are using. OpenCore developers have released approx. 60 compilations and some of them are incompatible with the previous ones due to the importance of the changes made.
The files that you have to renew when changing version are:
- EFI / BOOT folder
- EFI / OC / OpenCore.efi file
- contents of Drivers and Tools folders.
In 0.6.9 Bootstrap folder is no longer required.