We just found (and fixed) a serious problem in the Jul2017 releases that can result in database corruption.
So far we have only seen the corruption occur after a database (mserver5) restart. We have not yet seen a problem with a server that continues running (but unfortunately no guarantees).
We will create a new release candidate with this bug fixed as soon as possible (that will be version 11.27.9, i.e. anything in the 11.27.X series older than this is affected).
Currently known work around is to *not* restart the server, but keep it running, and creating a dump of the database using msqldump. This dump will then have to be restored into a fresh database in a server that is not affected by the bug (Dec2016 release or the upcoming Jul2017-SP2).