They remain in place and are selectable but won’t show up until selected.
How do you fill an unclosed object? It becomes 1-dimensional.
I’ve run into this behavior myself, but it makes sense.
It’s on the list to fix. We don’t recommend using ‘filled rendering’ for much other than spot checking partially because of this. Determining whether a shape is closed or not is complex - it came up recently here:
Thanks. I looked for a similar post but missed it.
No hidden meaning there, just pointing you at something that explained it a little better.