We have a scheduled Preventive Maintenance ticket that has run three times now, the first time one of my colleagues picked it up but it is no longer in the system. I do not "know" if he merged it with a previous ticket or just deleted it. The second ticket has also disappeared, i suspect that he just deletes them.

There are new requests from our customers that shows that the pmt has not been performed.

There is a fourth occurrence that will be triggered this week.

Is there any way i can find out what happened, except for asking him (he lies and also has not yet understood the meaning of using a ticketing system). I will need hard proof to show my manager so that this behaviour stops.

Does merged tickets not show up when you search for the ticket number? Will it show if i search for something other than default search?