JQL issueLinkType is inconsistent when using != or NOT IN operators when weblinks are part of issueLinkType

Issue Summary

When filtering issues by issueLinkType the results are inconsistent when using the != and NOT IN operators when weblinks are part of issueLinkType.

Steps to Reproduce

1. create a project, BUG
2. create two issues BUG-1, BUG-2
3. link BUG-1 to BUG-2, i.e. BUG-1 blocks BUG-2
4. search with JQL - project = BUG and issueLinkType != clones, both issues are listed
5. now add a ‘weblink’ to BUG-1
6. repeat the query, now BUG-1 is not returned while BUG-2 is still there.

Expected Results

The != or NOT IN operators should return the difference between the first and second queries.

Actual Results

There is not output with the results.

Workaround

If the linktype has the weblinks in it, instead of using 

issueLinkType != "link_type_name"  

We can use the below JQL to fetch the data that should include all the linktypes except the one isn't required:

issueLinkType in ("link_type_name1", "link_type_name2", "link_type_name3" ...)