I have been mucking about, trying to construct a 'simple' project that shows this problem. No success, however I have gained a bit of insight into the 'symbols' window that might be helpful.
In a workspace with several projects, the symbol window display changes as I change the focus between the editor windows for different source files. It seems that the intention is to always show the most relevant symbols by assuming that each source file is associated with one, and one only, project so that the symbols displayed need only be the ones for the project that is associated with the source file that has the focus.
The assumption there is incorrect. The reason that several projects are present in one workspace is that they are tightly coupled - meaning, in my case at least, that the projects SHARE source files. So, if the focus is on a shared source file, the symbol window can get very confused
IMHO this feature is more confusing then useful and may be causing unnecessary problems for the symbols window. I would like to switch the feature off. I would be happy to see either all the symbols in the workspace, or the symbols of the active project, no matter what source file I happen to be looking at. This would, at the least, remove the annoying flickering in the symbols window as I browse around the source files, and maybe even "fix" the empty symbol window problem that is bringing my work to a halt.
Do you know if there is a way to switch off the feature where the symbols window displays the symbols for the project that a focused source file is assumed to belong to?