I have a custom boolean field that I've added to Files that I'm now trying to use in a SOQL query to pull all Files that are linked to a specific record where this custom field is set to TRUE. Here's my SOQL query:

SELECT ContentDocumentId FROM ContentDocumentLink WHERE LinkedEntityID = 'a00f400000RaXnDAAV' AND ContentDocumentId IN (SELECT ContentDocumentId FROM ContentVersion WHERE Send_to_Angeion__c = TRUE)

What's odd is that this query: 

SELECT ContentDocumentId FROM ContentVersion WHERE Send_to_Angeion__c = TRUE

Never returns any results, even when I've marked the Send_to_Angeion__c as TRUE on some records. And even more interestingly, this query 

SELECT ContentDocumentId, Send_to_Angeion__c FROM ContentVersion WHERE ContentDocumentID = '069f400000Azta2AAB'

will return results and lists the value in the Send_to_Angeion__c as "true" Any ideas on how I can fix this? 

TIA