Some features of the displayed fields could not be filled.
When using temporal trend as the method to fill missing values, the location with a null value being filled must have at least two time periods with values at the beginning and at the end of the time series in order to be filled. The most common reason for failing to fill is the temporal trend with missing values at the start or end of the time series.
Another common reason for failing is an insufficient number of neighbors. Some features might not have enough or any neighbors to estimate the missing values. For input polygons with contiguity using edges or corners as the conceptualization of spatial relationships, there can be features that do not share a boundary with another feature. For fixed distance as the conceptualization of spatial relationships, there can be features that do not have any neighbors in the specified fixed distance. Missing values cannot be estimated for features with no neighbors or if all the neighbors have missing values.
No action is required. However, you can fill all values by changing the conceptualization of spatial relationships or fill method.