What are the annotation scales (not dimscale) of the dimensions that are going missing vs the scale of the viewport you are dragging on to the sheet. If these are different they won't show because AutoCAD recognizes you are placing a different scale drawing than those annotations were placed for. Even if it's off by a little bit the dimensions will go away. (i.e. the annoscale is 1/4" and the viewport is scaled to .487 instead of .48, something that's easy to do if scaling viewports manually vs dragging and dropping named modelspace views)
The annoallvisible variable turns this feature off when set to 1. I don't recommended you keep it that way however, I was only suggesting it as a way of discovering if this was the problem.
You don't need to select the dimesnions, because Annoallvisible is a system variable. You should be in the paperspace mode of the layout or sheet that you're having problems seeing the dimensions in when setting this, not the drawing where the dimensions were created. My apologies for not being clearer.
Also note it's annoallvisible and not allannovisible. Since you said you were able to set it I think you were simply mistyping in your reply, but it pays to be certain.
