I sympathize with your frustration.
I also encountered the same issue which ended up costing me a significant amount of time. Thankfully, I managed to discover the solution.
The culprit behind this problem is the latest version of Bootstrap. To resolve it, please carefully follow these steps:
- Begin by right-clicking on your project and selecting "Manage NuGet Packages":
https://i.sstatic.net/64T3o.png
- Locate the bootstrap package, click on it, and then navigate to the version selector on the right side. Click on the dropdown arrow:
https://i.sstatic.net/OdaLo.png
- Choose an older version of bootstrap (preferably 3.3.7) from the list:
https://i.sstatic.net/5wYpj.png
- Click on the "Update" button to apply the changes:
https://i.sstatic.net/4o7Hl.png
- You'll notice that the selected version of "bootstrap" has reverted back to the older one:
https://i.sstatic.net/E3vAP.png
- Don't forget to refresh your web page to see the changes take effect.
If possible, avoid repeating these steps unnecessarily.