The new general ledger engine was introduced in May. Changes made possible by the new engine have been rolled out since. Users are just noticing some of the effects in recent weeks, and particularly as they come to the end of accounting periods.
From the introduction post in the bugs category:
The program is not broken. It functions consistently and as designed. It includes in the General Ledger Transactions report line-item descriptions on postings from transactions created by the user. In the cases @VACUUMDOG complains about, the postings were internally generated without user involvement. Such postings do not include line-item descriptions, so they cannot be included in the report. The program cannot display what does not exist.