This will require Builder privileges for setup and implementation.
Scorecard chart symbols implemented as arrows in the data column only recognize if a value is: negative, positive, or neutral. They are incapable of tracking changes to a specific data set such as trends. The way the symbols currently work is based on the value of the column. If the value is: negative the arrow will point down, positive the arrow will point up, or is neutral (zero) the arrow will be horizontal.
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If the above is unable to resolve the issue, then please contact iDashboards Support for further assistance.