Even though the curve block is set to range between 0-100 the block just stays at a fixed output somewhere in the curve output range.
TAC Vista, SmartStruxure Solution
The curve requires the first entry of the X value to be the lowest value and then the subsequent values to be larger than the previous X entry.
Adjust the order of the XY entries on the curve block so the first entry in the X will be the lowest value.
Here is an example of a Curve that will not work. Note the first X entry is -2 and the last X entry is -6.
To correct this curve -6 is the lower number so this should be the first X entry
Here is a example of the curve that has the correct X entry order