For several users the pEp mode isn't working anymore, as some already pointed out at the Enigmail Forum
In my case this occurred one or two weeks ago. Before it was working without problems for several month. I already tried deactivating other plugins, reinstalling pEp-Engine and Enigmail - no success.
pEp JSON Adapter version 0.14.1 "(39) Gemünden". package_version="1.0.24"
pEpEngine version 0.9.0
I attached a (anonymized with XXXXX) logfile covering start, switching to forced pep mode and then sending the message (from 15:48:02)