when using Pixelated within Bitmask, no mails show up in the Inbox in the first run

when receiving mail with latest bundle, no mails show up in the inbox.

The error that appears in the log is: NoneType object has no attribute 'replace'

2017-03-13T19:07:17+0100 [leap.bitmask.mail.incoming.service#info] processing decrypted doc
2017-03-13T19:07:17+0100 [leap.bitmask.mail.incoming.service#info] maybe decrypting doc
2017-03-13T19:07:17+0100 [leap.bitmask.mail.incoming.service#info] maybe decrypting inline encrypted msg
2017-03-13T19:07:17+0100 [leap.bitmask.mail.incoming.service#info] adding message 7f4f5d4c-2a9d-4ffc-9358-2f344553232e to local db
2017-03-13T19:07:17+0100 [leap.bitmask.mail.incoming.service#error] Unable to format event {'log_namespace': 'leap.bitmask.mail.incoming.service', 'log_level': <LogLevel=error>, 'log_logger': <Logger 'leap.bitmask.mail.incoming.service'>, 'log_time': 1489428437.032638, 'log_source': None, 'log_format': <twisted.python.failure.Failure twisted.internet.defer.FirstError: FirstError[#2, [Failure instance: Traceback: <type 'exceptions.AttributeError'>: 'NoneType' object has no attribute 'replace'
        site-packages/twisted/internet/defer.py:1357:gotResult
        site-packages/twisted/internet/defer.py:1344:_inlineCallbacks
        site-packages/twisted/internet/defer.py:459:callback
        site-packages/twisted/internet/defer.py:567:_startRunCallbacks
        --- <exception caught here> ---
        site-packages/twisted/internet/defer.py:653:_runCallbacks
        site-packages/leap/bitmask/mail/incoming/service.py:854:_add_message_locally
        site-packages/leap/bitmask/mail/mail.py:628:add_msg
        site-packages/leap/bitmask/mail/adaptors/soledad.py:651:set_mbox_uuid
        ]]>}: Log format must be unicode or bytes, not <twisted.python.failure.Failure twisted.internet.defer.FirstError: FirstError[#2, [Failure instance: Traceback: <type 'exceptions.AttributeEr
ror'>: 'NoneType' object has no attribute 'replace'
        site-packages/twisted/internet/defer.py:1357:gotResult
        site-packages/twisted/internet/defer.py:1344:_inlineCallbacks
        site-packages/twisted/internet/defer.py:459:callback
        site-packages/twisted/internet/defer.py:567:_startRunCallbacks
        --- <exception caught here> ---
        site-packages/twisted/internet/defer.py:653:_runCallbacks
        site-packages/leap/bitmask/mail/incoming/service.py:854:_add_message_locally
        site-packages/leap/bitmask/mail/mail.py:628:add_msg
        site-packages/leap/bitmask/mail/adaptors/soledad.py:651:set_mbox_uuid
        ]]>