You may get some insights into the geocoding issue by examining the geolocation metadata for the “black” tiff. GIS packages often have logic to deal with inconsistent geolocation metadata. Have you tried loading the geotiff file in a GIS (QGIS is available to all so a good choice). You can also use gdalinfo in a terminal window to display the metadata.
This is a common error when working with dates in Java. You can many discussions on
the internet. Others have reported “Unparseable date” errors with SNAP, but the reports lack the detail needed to reproduce the issue. Are you using SNAP 9? What OS? What input data?
RAM problems generally reveal themselves in very slow performance or out-of-memory errors.