Snippet output in Multi-select Setting in a Content Block is empty, but the same Snippet on page & in TV returns output

I have a snippet call in a Content Block Setting which uses an API to create a list of available Events. I have verified that the Snippet works, and that the output is in the correct format for the Multi-select setting field.

I have succesfully created the same Snippet to return the list of Events into a Multi-select TV, and it works on evey page load successfully. I’ve manually added the exact same data as the API data in the snippet, and when I return that, the Multi-select is populated, so I know the formatting and data is correct.

From what I can see, when the Content Block loads it doesn’t load the Snippet data from the API, as a var_dump in the setting gives me array(0) but in the same snippet call on the page (and the TV on the same page) I get array(14) .

I have tried to call the snippet uncached, but that just returns the snippet as text, even if you check the Proces Tags box on the setting.

I know I can use the selected TV values on the page and use that in my Content Block, but I don’t want to do that as I am likely to have the same Content Block on the page with different options selected.

I am guessing that this is to do with the System Events and order that Content Blocks “builds” out the page, but I am just guessing here as I have no clue as to how I can fix this.

Any help/advice is always welcome!