By reviewing the processing time reports, it appears that the I485 (employment based) processing has been completed halted for at least the last 6 months.

Why has this happened, and is there any hope for the future? When will it start up again?

For each category there is a numerical limitation as to how many visas will be issued in a calendar year. It looks like BCIS had exhausted all employment based visas. As from October 01, BCIS will start issued visas when their new year will start.
Good luck.