DynamoDB Scan returning an empty array

I'm attempting to utilize a Java program to interface with DynamoDB to retrieve a primary key and eventually turn it into a list of strings so that it can be sent over as a POST request to a website that needs these details. I'm able to send over hard coded arrays up to the frontend website, and it's rendered nicely. However, attempting to scan and retrieve a primary key string in each item of the table yields an empty array. Any help would be appreciated. The table only has a few items.

public List<String> getAllImageIds() { //HomeScreen_Entity.java
		
		ScanRequest scanRequest = new ScanRequest()
				.withTableName("tableName")
				.withAttributesToGet("image_id");
		ScanResult result = dynamoDBClient.scan(scanRequest);
		List<String> imageIds = new ArrayList<>();
		for (Map<String, com.amazonaws.services.dynamodbv2.model.AttributeValue> item : result.getItems()) {
			if (item.containsKey("image_id")) {
				imageIds.add(item.get("image_id").getS());
			}
		}
		System.out.println("The first item in imageIDs is: " + imageIds.get(0));
		return imageIds;
		
	}