There seems to be a glitch displaying the glyphs

Please look at the two screenshots. The further I scroll up or down the more glyphs sre being displayed. On the right glyph-displays are cut in half.

Is that the latest version (983)?

What happens when you resize the window, change the scale (slider in the bottom right corner)?

Perhaps try getting rid of the sortOrder parameter in File > Font Info > Font > Custom Parameters. (Select, click the minus button.)