Chemical structure of trivial molecules appear without their nodes when using flagging

[EliotRagueneau]

e.g. https://reactome.org/beta/PathwayBrowser/R-HSA-975634?select=R-HSA-975634&flag=class:Complex!drug&path=R-HSA-1430728;R-HSA-196854

Should have the trivial node presents when initially loading a diagram with flagging, and not hidden.