.Net自定义TraceListener.TraceEvent未触发

We have a custom TraceListener (inherited from System.Diagnostics.TraceListener) which we use for our ASP.NET web application logging. It's been working great - no issues. Then all the sudden it stopped working in our dev environment (TraceListener.TraceEvent() stopped firing). We are baffled as to why it stopped working. The only changes we really made in code was added more build configurations (Dev, Test, Stage, Prod). Before, it only had Debug and Release.We have a custom TraceListener (inherited from