How to access post meta from custom post type

I’m using:

–ACF 6.1.6
–GenerateBlocks 1.7.3

I’m familiarizing myself with the dynamic data feature and how best to access data from custom fields created with ACF.

I believe the ACF custom fields should be under:
Data Source (Current Post) => Content Source (Post Meta) => Post Meta Field (Choose or add meta key)

The Post Meta Field dropdown is empty. The text below says: “Live preview is only available to meta exposed to the REST API.” I believe I have correctly toggled on “Show in REST API” in the settings for my ACF group.

I am able to manually enter the meta key, which shows the meta key in the admin and the value in the front end.

I would like to get the live preview of the meta fields in the dropdown with preview of the data in the admin when laying out the page design. Is this possible?