I can’t be sure what is causing the exact problems you are experiencing, but it is most likely related to how the interactors work right now. Since they don’t by default work well with occlusion, partial or full, I would recommend to roll your own solution for interactors until we have a working solution (which is still in an underterminant amount of time in the future I’m afraid).
My best naïve solution so far has been to first test all actors in the scene against a convex shape (frustum works best of course) I align in the direction of the gaze point and then to iterate over the actors I found and test a raycast against each one to test for occulsion. This of course still doesn’t work well with partial occlusion, but at least it is fast enough to make it workable until I can get the budget to do the good solution.
If you are working in blueprint only, I think the best way would be to simply spherecast instead of doing the convex shape test, but this will have really bad results to objects far away.
Both of these naïve methods are actually in the SDK, although not in their latest versions (in EyeXMathHelpers.cpp I believe).
If you tell me more about the game scenario I might be able to give you more directed tips for that, but as a general rule I think this is as good as it can get until the good solution.
If you have any questions on how to get this into the game, please tell me and I could probably put together and send you some sample code that makes it a bit clearer.