OJS 3.1.1-2 Cannot load record: invalid representation id

Hi,
I have a problem regarding the user statistics scheduled task, since a few weeks
The task allways aborts with the error message:

[2018-08-16 12:29:42] [Error] Cannot load record: invalid representation id.
[2018-08-16 12:29:42] [Notice] Task process stopped.

I have no clue why this is happening, but I did some debugging and found out the id, where the error ocures (It is always id 1).
As far as I know the representation id is the gallery_id in the submission_galleys table and there is indeed no entry with gallery_id 1.

Kind regards