Hey,
For a test, I have two issues: Issue One and Issue Two. Issue Two "is blocked by" Issue One, by creating a link between those two records.
If I do the JQL statement: issueLinkType = "is blocked by", Issue Two is correctly the only issue that is returned. Here is a screenshot of that query:

However, when I execute the JQL Query: issueLinkType = "blocks", (lower-case b, to distinguish it from "Blocks"), instead of only returning issues that block other issues, it returns all issues that are either blocking, or being blocked--in the example, both Issue One and Issue Two are returned. Here is a screenshot of that query:

(1) How can I create a JQL query that will only return issues that block another issue, or (2) is this just a bug in how the "blocks" keyword behaves, at the moment?
Here is a quick video demonstration of the issue, in case anything about this question is unclear: Link to quick YouTube video demonstrating question
I've tried issueLinkType != "is blocked by", but that doesn't return anything.
Thanks, let me know if anything could use clarified.