You are trying to pull data from a previous automatic collection action into another action (eg, a Reminder) but when you go through the process the data is missing or incorrect.
You might have a process similar to this, where the Reminder is expected to take the data from a previous collection action, in this case "Task 1".
This comes down to the way Service Desk performs and evaluates the process, in particular when there are automatic actions present.
A placeholder retrieves the latest data from a collection, and when you add to that collection at the same time as trying to take data from it, such as adding Task 2 to the Task collection while the Reminder is being evaluated in the example above, you will see the data from the latest record, ie, the one you just added, even if it comes after the action containing the placeholders in the process.
If you put a manual action anywhere between the action containing the placeholders (ie, the Notification) and the second automatic action (eg, Task 2), or if you remove the second Task altogether, the placeholders evaluate correctly.