Cmd-opt Alias dragging is buggy/inconsistent

I am using figure aliases in the research binder, cmd-opt-dragging figures from the finder into the binder. This works great except that much of the time cmd-opt-dragging brings the original figure, rather than an alias (with a little arrow in the lower left). I like using aliases because I can modify the original figure and get the change to show up in the document. Sometimes if I cmd-opt-drag to another folder I get an alias, but the behavior has been getting worse and worse (i.e., fewer and fewer real aliases resulting) over the several days I’ve been doing this.