1. Multiple times I was stumbled why some policies wouldn't work - until I realized that the expressions had some invalid syntax yet the TryExpressionBuilder was hiding the exception:

IMO we should log the error using the standard logger... I am also not sure why there is no try&catch around CompileExpression() - as there could be errors in there as well.

2. FYI - the actual Interpretor (DynamicExpresso) has known issues with single quotes - might be useful to change those before the actual evaluation to double quotes, e.g.

expressionString = expressionString.Replace('\'', '"');

Thanks