We have bug CSCvt15893 for this issue .You can reach to out TAC ,they will share HP to fix the issue .otherwise they can run reset of Mnt DB will fix the issue ,they will loss the old data .
Just check have you selected the log collector for passed and failed authentication on logging categories.
If you are not selected ,then please select it and it will stop.
Could you please let us know ,whether you are looking for .log files to deletion based on rules or reporting also to delete . If want to reduce the diskspace of Mnt server ,then you can configure the database purge by default it is 90 days...
Could you please check whether do you have PLUS or not ? if don't have PLUS license ,then check profile service option is enabled from GUI or not ?
If it is enabled ,then disable it and try to delete to it ,then it will work fine .