I have to tell you, i didnt think it will be an issue, since somewhere down the path, selectAll uses a list a model indices which have to be set to selected and which are available at that exact moment. Now, it may happen that by the time the view updating occurs, there are many more actual items in the model, and thus, more indices, but there are never less, and i dont see how the originally selected indices could become invalid.
What is my misconception about all of this?
First of all, all I said is just a guess. It is pretty hard to state some facts.
Second of all, you misunderstood me.
I was trying to say that it is possible to have a discrepancy between the number of indexes in the model and the number of items actually painted in the view.

When you call selectAll, it will try to select N items in the view, while the view contains only M items, where N >= M.

So, this could even be a stupid idea, but it would be great if you could do some debug to see if it is true, or even implement it, it's not a big deal.