Why Custom Column Values can Differ from Chart Values
These indicators may be "cumulative" indicators. A cumulative indicator is one that builds upon itself (using its own previous value). For example, any indicator involving an exponential smoothing fits into this "cumulative" category. When an indicator is cumulative, its value is dependent in some way on all previous data elements that are considered in the calculation. While the chart is loading a certain number of bars (depending on the chart's viewing period), the custom column is loading a minimal number of bars for efficiency reasons.