If macro {ITEM.VALUE} is used on trigger description, it does not keep the value when the problem was created, but gets updated with latest value.
Example:
Trigger configuration:

First value 6 was sent to the item, the problem was triggered and showed 6 in both, problem name and problem description. Later value 7 is sent to the item, this is what is shown:

Expected result:
As per documentation:

1) the historical (at-the-time-of-event) value of the Nth item in the trigger expression, if used in the context of trigger status change, for example, when displaying events or sending notifications.