Why aren't apps listed as available in admin when adding a new block?

[shellbryson]

1. Created a new cart.json file

2. Created a new main-cart.liquid file, with appropriate case/when, with the following JSON (partial)

In admin, when adding a new block, no Apps are listed… however if I manually create an app ref in cart.json, it appears. Why is admin not listing apps as being available!?

(only “add infocard” is available, rather than “add block” as it is ignoring the @app section of the JSON)