Filenames that start with YYYY-MM-DD in collections seem to be problematic when there is more than one file with the same date. This is probably some relic of the fact that Jekyll started out life as a blogging engine -- Jekyll blog posts are expected to start with the YYYY-MM-DD date. It seems that the files are read and processed into the collection (therefore internally known to Jekyll), but the files for only one item on the same date are generated.
It seems like a workaround is just to collapse the date structure if you want to start with a date (YYYYMMDD). Another workaround is to lead with something else -- like an abbreviation for the series. This also has the benefit of grouping the events belonging to a given series in the directory.
Filenames that start with YYYY-MM-DD in collections seem to be problematic when there is more than one file with the same date. This is probably some relic of the fact that Jekyll started out life as a blogging engine -- Jekyll blog posts are expected to start with the YYYY-MM-DD date. It seems that the files are read and processed into the collection (therefore internally known to Jekyll), but the files for only one item on the same date are generated.
It seems like a workaround is just to collapse the date structure if you want to start with a date (YYYYMMDD). Another workaround is to lead with something else -- like an abbreviation for the series. This also has the benefit of grouping the events belonging to a given series in the directory.