This is your original art? Can you upload the file if so?
Try doing a select all (control/command-A), it’ll put a rectangle around the entire pieces. Its possible that your lines and other oval are offscreen.
If the select-all selection rectangle is completely visible on screen and you still don’t see the 2 missing shapes, it’s possible that they are tiny, and thus not visible in the UI. The source art would really help.
In any case, your instinct about the stroke width was a good guess but not the case here, the UI doesn’t care about stroke width.