Measures of a table object (pivot table or straight table) change value after reloading exactly the same data. This change of measure value depends on selections that are currently applied to the table dimensions.
See the attached Zip file for a demonstration app and screenshots.
This is a known limitation (since QlikView 10) where multiple SET expression(s) relevant to separate logical islands are used in a single expression. This will result in a Cartesian product of the two dimensions and the inference between these logical islands, state invariant SET expressions and this Cartesian. Geometrical dimensionality works well with static data, but may not be fully expanded when the underlying data is changed (through a reload) and, on top of that, intersected by a selection.
This limitation has been considered in bug QLIK-83513. However, the bug is concluded as Won't Fix because fixing this is a fairly major task combined with a high level of risk.
Review data model to see if the affected measure is using fields from multiple data islands (i.e isolated tables that have no direct/ indirect association links to each other). For example, in the attached sample app, the expression uses two fields Value
which belong to two different unconnected tables.
In this situation, best practice is to join the two tables to explicitly define the association logic between them.