Hello, I'm sorry you're having this issue and about the delay in my response, as of right now I'm not entirely certain as to what's causing this to happen. It's something I've never seen happen myself, I do have a few ideas of things to test but this internet outage on the east coast has had me all backed up. I hope to have enough time tonight or tomorrow morning to try fixing this, if possible could you provide a video of it happening? And maybe try disabling any other title screen plugins you may be using, if any, and see if there is a possible conflict.
When it blinks black, can you still see the menu while it's black or does that disappear too when it's black?
If the title menu disappears too when the screen blinks then I might have an idea of what may be causing it, though I've never had any issues with this particular feature before but maybe it's the fade out + fade in acting in an unexpected way for some reason. I could comment out that part of the code and see if that resolves the issue for you.