If you look at my testers, there are some failures that have very unhelpful output.

For example:
(which shows as a failure on the main 'develop' page)

Shows four links (for C++11, 14, 17, and 2a). So far so good.

Test output: Marshall-UBSAN - beast - _detail_base64 / clang-darwin-ubsan
Rev af4cfb1e2cdae70cbda8ff73eca8724cb4538dd6 / Sun, 24 Mar 2019 14:52:01 +0000
Lib [2019-03-25 10:04:36 UTC]: fail
See boost/bin.v2/libs/beast/clang-darwin-ubsan/debug/cxxstd-11-iso/link-static/threading-multi/visibility-hidden

ok, this says it fails. Fine.

Clicking on that link gives you the following output:

Test output: boost/bin.v2/libs/beast/clang-darwin-ubsan/debug/cxxstd-11-iso/link-static/threading-multi/visibility-hidden
Rev af4cfb1e2cdae70cbda8ff73eca8724cb4538dd6 / Sun, 24 Mar 2019 14:52:01 +0000
Link [2019-03-25 10:04:36 UTC]: succeed

  "ar"  rc "/Sources/boost/testing/results/boost/bin.v2/libs/beast/clang-darwin-ubsan/debug/cxxstd-11-iso/link-static/threading-multi/visibility-hidden/libstatic_beast.a" "/Sources/boost/testing/results/boost/bin.v2/libs/beast/clang-darwin-ubsan/debug/cxxstd-11-iso/link-static/threading-multi/visibility-hidden/test/_lib_beast.o"
  "ranlib" "-cs" "/Sources/boost/testing/results/boost/bin.v2/libs/beast/clang-darwin-ubsan/debug/cxxstd-11-iso/link-static/threading-multi/visibility-hidden/libstatic_beast.a"

That says that it succeeded. 
However, the previous page shows that it failed.
Which is it? I don't know.

Any suggestion on how to figure this out / improve the results?

-- Marshall