UE5 Early access RegEx in Build.cs scripts not working


There seems to be an issue when I try to use C# regular expressions in the new UE5 build system - namely the Build.cs scripts with RegEx that were working in UE4 are not compiling in UE5.

One of our clients investigated further and they said: “The Build.cs scripts cannot use Regex expressions due to a change in how they dynamically compile the Build scripts for .NET Core.”

Is there a chance this is not working due to a bug / oversight to the new build system, or is this done intentionally?

Best Regards,
Nick J, Coherent Labs