Bug: on occasion sidebearings are indicated wrong

i noticed that sometimes the sidebearings can be displayed with wrong values, maybe zero but sometimes something else, if i wiggle the shape it notices the mistake and updates the values.

however in this case this glyph is in use for metric keys which has implications of showing other glyphs out of sync aswell, and potentially inheriting the wrong values.

even if this is temporary, or easily fixable its kind of annoying

Can you reliably reproduce it?

sadly no. but it reoccurs.