Concrete5 + Opencart = partial Google render

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I have an issue with Google only returning a partial render of my site before indexing.
I have my C5 files in the root with the homepage links branching off to an Opencart shop in a separate directory.
Is there a quick fix so I get a complete render?
I don't know if it is safe to remove lines from the robots.txt file without compromising site security.

trixiemay