Glad you're enjoying it!
Removing the ear clips is an intentional choice. I've explained this elsewhere, but I understand the comment section is getting a bit long at this point. It's a meta thing: Mezz forgets about the clips the moment they're on, but the player can toggle them on and off to turn off the battle sex if needed/desired. This is only mildly useful currently, but my hope is that the next chapters will be a bit larger, so it may be useful to be able to just do some fights quickly and get them done if you're repeating an area for example. Of course the clips won't be in the next chapter, but the same general design principles will carry over.
Mezz is still "under" at the end of the loop after returning the clips because the control isn't solely in the clips. It just starts there, and the clips allow for deepening and fine-tuning.
I may do more with slut mode and the boss interaction eventually, but we'll see how it turns out.
If you mean a very brief invisibility, yes, that's a sprite sheet issue. There are also a number of rare oddities with the battle engine, but I hope to have it at least a bit more smooth next release.
And thanks!