If a node doesn’t become opaque in Show Events mode, or if its port popover says “Last Event: (none observed)”, then the node isn’t executing. If a node isn’t executing, that means events aren’t reaching it. Here are some things to check:
Is there a trigger port connected to the node? Trace backward through your composition, starting at the node that isn’t executing, and looking at the cables and nodes feeding into it. Do you find a trigger port? If not…
Add a node with a trigger port, such as Fire on Start, and connect the trigger port to the node that isn’t executing.
Is the trigger port firing? Check the trigger port’s popover (or connect a Count node, as described above). If the trigger isn’t firing…
Check the node description for the trigger port’s node. Make sure you understand exactly when the trigger is supposed to fire.
Check the trigger port’s event throttling, which is displayed in the port popover. If it says “drop events”, try changing it to “enqueue events”. (See the section Buildup of events.)
Are events from the trigger port reaching some nodes but not others? Trace forward through your composition, from the trigger port toward the node that isn’t executing, and find the last node that’s receiving events.
Look at the input ports on that last node. Do they have walls or doors? (See the section Event walls and doors.) Check the node’s description to help you understand when and why the node blocks events. To send events through the node, you may need to connect a cable to a different input port.
Look at the output ports on that last node. Are they trigger ports? Remember that events into input ports never travel out of trigger ports. To send events through the node, you may need to connect a cable to a different output port.