The section marker with no 'open' option must be and 'unlinked marker' type section ... simply a 2D symbol. See attached. Select the section marker, do a ctrl-T/cmd-T to see the settings and check there. (Depending on your Info Box setup, you can check there as well.)
Cheers,
Karl
One of the forum moderators
AC 27 USA and earlier • macOS Ventura 13.6.6, MacBook Pro M2 Max 12CPU/30GPU cores, 32GB