When using the CSV export to write data into a text, some exported pixels contain zero values.
Example data is on the test server:
The product subset_ESACCI-LC-L3-SR-MERIS-300m-P7D-h37v10-20090730-v1.dim contains 25 (5x5) pixels which have been exported to subset_ESACCI-LC-L3-SR-MERIS-300m-P7D-h37v10-20090730-v1.csv.
Only the first row of the csv file contains data.
This happens because
The buffer retrieved from the source band is bigger as the scene size of the product.
The buffer has the size of the default tile (e.g. 512x512). Pixels outside of the scene area are initialised with zeros. This leads to the result that only the first row has values and the rest is filled with zeros.