Version 2.4.2 (1009).
It does not occur every time, but occasionally the smart component glyphs (with the “_part” prefix) would lose its defined value for every layers.
When this problem appears, the properties are still there. Just re-assign the value for the layers, all glyphs using these components will return to what it should look like.
It does not only happen in re-opening. Once I copied and pasted a modified smart component in a single file, it returned to its shape in main layer. Problem is also solved by re-assigning the property value in the “_part” component glyph.