I remember seeing this behavior on MV. But I thought that was fixed on MZ.
I can take a look at it, but I don't remember seeing on code something that can cause this issue.
Either way, I believe you can find a workaround by using my Bitmap Plugin. It does have a free version for you to test it. It has a little setup since you need to create your own font by using an image editor. But I believe it can solve your issue.