Here's a patch on a base commit with --repeat=10 that fails to get any dumps from any of the tests.
Running the hang-analyzer does work locally though, so the problem is not with the LLDB commands themselves, but probably a build/versioning issue.
TIG-859 also is a LLDB problem, but these seem to be unrelated issue. In TIG-859 the hang-analyzer does generate some dumps, but not all. The problem I saw above was that LLDB seemed to do nothing at all.