If statistics and a histogram are not available for the input raster, they are computed for the default reclassification (remap) table. If the input raster has more than 4,000 rows or 4,000 columns, a skip factor greater than 1 is applied.
When a skip factor is applied, it is possible that some cell values in your input raster (that is, minimum or maximum) will fall outside of the range of values in the remap table. This may result in cell values in the output raster that were not included in the reclassification.
If necessary, use Calculate Statistics to ensure the raster dataset has the appropriate statistics (and histogram).
Optionally, you can manually enter or modify break values for your remap to be within the full range of input values. You can control whether missing values retain their value or get mapped to NoData using the missing_values parameter of the Reclassify tool.