There were a number of mapping issues introduced by version 4.3.0. None of the changelogs for versions released since then (including 126.96.36.199) indicate that they've addressed the specific issue described in threads like these:
In fact, the changelog for 188.8.131.52 doesn't say anything was fixed.
The issue at hand is a major bug that effectively broke every mapped site in our networks and forced us to roll back to 4.2.06. I'm reluctant to update to any of the new versions for fear of reintroducing the bug.
Please let us know.
PS - The changelog shows a release date of February 2, 2015 for every version of Domain Mapping since version 4.3.0. This is inaccurate and should be corrected.