OJS - Articles disappeared from published issue and archives

The editor of a journal we host contacted us this morning, saying that after publishing her new issue, the preceding issue was emptied of all content. I have verified that the issue in question still shows as published, but it no longer contains any articles. The articles that had formerly been published in it no longer appear anywhere in OJS, including the archive. In effect, they seem to have vanished without a trace:


I haven’t been able to find anything comparable reported on the forums since the issue with articles disappearing when their sections were deleted was fixed a couple years back. Any insight on what might be going on here would be greatly appreciated. We have backups of the content and can restore it, but one gets a little nervous any time large quantities of data go missing unexpectedly.