There was a bugfix released in EPiServer.CMS.Core 9.8.1 that might solve your issue

http://world.episerver.com/documentation/Release-Notes/ReleaseNote/?releaseNoteId=CMS-3218

Hi Johan,

Thank you for your reply,

Unfortunately we are not in position to upgrade your Episerver application to that version yet. In the meantime, would you consider running the "netActivityLogTruncate" stored procedure as SqlServer job safe?

(I presume that's what the "Change Log Auto Truncate" Episerver job does under the hood.)

Thanks,

Frank

It is possible to run the sproc manually, it is though not officially supported, with that said:

Currently there are a few functions that are dependent on the change/activity log. First there are the two jobs BlobCleanupJob and CleanUnusedAssetFolderJo, so I would suggest that you execute them before running the procedure. 

Then there is mirroring, same applies there if you are using mirroring, execute that job before truncation.

The last thing that has a dependency (at least in CMS, I am not aware if any other addon/module are dependent on the activity log) is projects (which might be the thing that prevents the truncation job from truncating anything). What will happen if you run the truncation script is that things that are dsiplayed in project overview will disseapear. So the suggestion is to execute the procedure with a Date set for parameter @CreatedDate where you can select the date from how old project entries that should be shown.

Thanks for the explanation Johan!

I intend to leave at least 2-3 worth of latest log entries anyway.

Thanks,

Frank