Yes, this is currently a bug with how and when saves occur.
I remember in classic we used to get a periodic message such as "Reynard saves." and I found it so unusual at the time. After experiencing this bug a few times, I would love to know when we do indeed save so that I know when it is safe to log out or zone since those are the times when the "disappearing item" bug occurs.
This has been discussed in these posts:
Items disappearing from inventory
and,
More items disappearing from inventory
as well as passing mention of this issue in various other threads which were begun as new threads instead.