MSAA rendering problems

Hello, guys.
I found an interesting phenomenon when using MSAA in Unreal 4.14. I rendered a scene with a window and you can see through it. Notice the image with red arrows, you can find white patterns about a single pixel wide, which looks like aliasing. This kind of artifact appears only in a MSAA mode. When I switched to TAA, the picture rendered like the second one. However, in my project I have to apply MSAA.
I want to know the cause of this artifact. And in MSAA, what can I do to improve this?

Thank you very much!

I found out (from these forums) that the MSAA implementation currently only takes geometry edges into account (not internal edges or transparency / opacity). Is it possible that these edges are internal to the geo (I.e your glass pane is in the same piece of geo as the frame)?