First off, if your network still shows dirty areas in the map (usually a purple box covering all or part of the network), you need to run the Build Network tool. This tool incorporates edits to the network dataset properties and feature geometry into the internal logical network. If you don't do this step and you try to solve network analysis when you still have dirty areas, any changes you made to the network might not get used. So, if you did something with your transit lines and didn't build the network, this might be the reason they are never used.
If that isn't the issue, then here are the typical reasons that the transit lines are not used:
- The date and time you chose for the analysis has no transit service. If you chose a specific date, and that date is outside the range of valid dates in the Calendars table, then there's no service. Or, if you used a generic weekday, but the Calendars file is empty, there will be no service because you have to use a specific date for this dataset.
- You have a connectivity problem. It's usually where the StopConnectors meet the streets. You can use the Explore Network tool to click on a stop connector and make sure it highlights the street it appears to connect to to show that it is actually connected.
- Your evaluators are configured incorrectly. If you used the provided template and didn't change anything, this probably isn't the issue, but it's worth double checking that for the PublicTransitTime cost attribute, the LineVariantElements edge source uses the Public Transit evaluator.
- You're using the wrong travel mode, or your travel mode is configured incorrectly. If you used the provided template and didn't change anything, this probably isn't the issue, but it's worth double checking that the travel mode you're using for your analysis uses the PublicTransitTime cost attribute for its impedance and doesn't have any weird restrictions that make travel on the transit lines restricted.
I noticed in your screenshot showing the table from Explore Network that the transit line is showing Prohibited in both directions. That makes it seem like a problem with your cost attribute, restrictions, or travel mode. Note that you can flip over to the Settings tab in the Explore Network pane and choose which travel mode to use with the tool, so I can't tell if you're just using the wrong travel mode in the tool or if this is actually a symptom of the problem you're trying to diagnose.
In case you haven't found it, here is the text version of the tutorial that the video you watched walks through: https://pro.arcgis.com/en/pro-app/latest/help/analysis/networks/create-and-use-a-network-dataset-wit... The text version has a bunch of links to other help pages that might be useful.
If you still can't get your network working, I recommend you contact Esri Support. They can examine your network in detail and help you find what went wrong.