jetpack_development_mode filter breaks Custom Content Post Types

Custom content post types (testimonials & portfolios) show up normally when JETPACK DEV DEBUG constant is used, however when the jetpack_development_mode filter is added through a plugin, the custom content types do not show up as they should.

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Steps:
* Install & activate Jetpack
* Install & activate plugin containing the jetpack_development_mode filter
* Active custom content types setting in Jetpack
* Enable the testimonials & portfolios custom content types in Jetpack

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Expected: Portfolios & Testimonials post types show up in the left-hand menu in the admin.
Actual: No menu item is added, when you go to the specific post type edit page, you get an Invalid Post Type error.