I ran into the same issue and none of the 'solutions' posted in this
thread have helped. After lots of testing, here is my conclusion.The
original editable PDF is created with Adobe Professional (with Extend
Features in Adobe Reader enabled). This PDF is then emailed to various
people. As long as each user opens and edits this PDF in Adobe Reader
(NOT PRO), the changes are saved and the next person can continue to
open/edit without any issues. If someone opens this PDF in Adobe Pro,
and then sav...