This should has been fixed now according to the issues trackers on GitHub. If you are still encountering this problem, please report to the project site on GitHub.
BTW, I've migrated to use Gulp to package my client resources. Refer to the following page for more details:
person G Swanson access_time 2 months ago
Re: ASP.NET Core 2 with Bootstrap 4 Bundler Minifier Issue: Expected semicolon or closing curly-brace found '-'
I am still getting the problem. What do I need to upgrade to fix it?
I am using Visual Studio 2019 and most of my nuget packages are pretty recent.