Shoveled all the settings for us on the FaceBook side.
It looks like everything is OK.
FB itself gives the following message:
"No action is required from you. If in the future you need to take any action on one of your applications, the corresponding button will appear here."
http://prntscr.com/uouar8That is, when third-party people contact the messenger,
as it should be, a process is created in OneBox,
but no message text is passed to it.
Is there a solution to fix this?