Accepted photos not appearing in group stacks?

So I had been wondering about this, but seem to have more evidence now. 

So as someone on dA, I join/watch groups, and submit pictures to those groups to get them seen by other members.  That's the fundamental basis of the way I use the site.

So normally/historically, when I submit a photo to a group and they accept the photo, I see my photo pop up in the "Watch" part of my notifications page, now in the "Group Deviation Stacks" section. 

However, lately, many times I will have photos accepted, but I will never see the photo pop up in that section.  Sometimes some of my accepted photos will, so it's not 100% in all cases. 

Does anyone know what's going on here?  Is there someway for either groups or individual members to pick what accepted pictures are displays in the "watch" section?  Because there is basically zero reason for me to submit pictures to groups if no one will see them.  Maybe it's just a dA bug?

Any information would be useful!

EDIT: It looks like it may be something where any individual deviation is only displayed in your group stacks once.  So when I submit to multiple groups, which ever one accepts it first, will show up in my feed (and not in the others).  Maybe they try to reduce redundancy that way?  I'm not sure, but I think that may be the case.