It seems that i have stumbled across a bug/feature in 4.12.2.
If i decide to nativize my blueprints, and an error occurs when cooking, i might then go back into the preferences and untick the ‘nativize blueprints’ option. At the point when i do this, the editor has created a bunch of C++ files within the project under Intermediate\WindowsNoEditor\NativizedAssets.
The problem comes when I then attempt to cook again, these nativized assets (which contain an error) are still built.
There is no way to prevent building of these generated files until I manually go into the NativizedAssets folder and delete it, as it seems the project automatically detects them regardless of the status of the ‘Nativize assets’ check box.
Furthermore, with the checkbox unticked they won’t ever be re-generated by the editor so will be out of synch with any changes made to the blueprints, although they will still be built. I am unsure what knock-on effect that might have.
On a related note i am obviously getting errors when trying to use the nativize blueprint feature which led to this bug report in the first place, but i will log those to a separate answerhub entry.
Thanks for any help you can give!