SYMPTOM:
When a user executes a report in Strategy Web, a metric on the report will disappear, however when executing the same report in Desktop the metric is displayed correctly.
Consider the following report as executed by the user in Strategy Desktop. Note that there are two metrics being displayed

When executing this report in Strategy Web, m2 is no longer present on the report as shown below.

CAUSE:
One of the underlying components of a metric has 'Deny all' set for a user or group. This can be for component metrics or custom totals.
In the above scenario a subtotal that was added to m2 had a ACL for the Everyone group set to 'Deny all'
ACTION:
Verify the security settings for any components of a metric including subtotals to make sure that the users have access to them.