Error when running WIP Report on multiple files

Hi,

When trying to run the WIP Report on several files at the same time, I get the following error for each file:

Unexpected exception when configuring file multiFileConverter for task 'WIP Report': An item with the same key

And the error report:

<SDLErrorDetails time="2018-12-05 23:33:33">
<ErrorMessage>Unexpected exception when configuring file multiFileConverter for task 'WIP Report': An item with the same key has already been added..</ErrorMessage>
<Exception>
<Type>Sdl.ProjectApi.ProjectApiException, Sdl.ProjectApi, Version=15.0.0.0, Culture=neutral, PublicKeyToken=c28cdb26c445c888</Type>
<HelpLink />
<Source>Sdl.ProjectApi.Implementation</Source>
<HResult>-2146233088</HResult>
<StackTrace><![CDATA[ at Sdl.ProjectApi.Implementation.TaskExecution.ContentProcessingTaskImplementation.TaskFileExecuter.ConfigureConverter(IMultiFileConverter multiFileConverter, Language targetLanguage)
at Sdl.ProjectApi.Implementation.TaskExecution.ContentProcessingTaskImplementation.TaskFileExecuter.CreateMultiFileConverter(IProjectFile tf, String filePath)
at Sdl.ProjectApi.Implementation.TaskExecution.ContentProcessingTaskImplementation.TaskFileExecuter.Parse(String targetFilePath)]]></StackTrace>
<InnerException>
<Type>System.ArgumentException, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</Type>
<ParamName />
<HelpLink />
<Source>mscorlib</Source>
<HResult>-2147024809</HResult>
<StackTrace><![CDATA[ at System.ThrowHelper.ThrowArgumentException(ExceptionResource resource)
at System.Collections.Generic.Dictionary`2.Insert(TKey key, TValue value, Boolean add)
at Sdl.ProjectAutomation.AutomaticTasks.ExecutingAutomaticTask.GetWordCounter(ProjectFile executingTaskFile)
at Sdl.ProjectApi.AutomaticTasks.WIPReport.WIPReportTask.CreateProcessor(ProjectFile file)
at Sdl.ProjectApi.AutomaticTasks.WIPReport.WIPReportTask.ConfigureConverter(ProjectFile projectFile, IMultiFileConverter multiFileConverter)
at Sdl.ProjectApi.Implementation.TaskExecution.ContentProcessingTaskImplementationAdapter.ConfigureConverter(IExecutingTaskFile executingTaskFile, IMultiFileConverter multiFileConverter)
at Sdl.ProjectApi.Implementation.TaskExecution.ContentProcessingTaskImplementation.TaskFileExecuter.ConfigureConverter(IMultiFileConverter multiFileConverter, Language targetLanguage)]]></StackTrace>
</InnerException>
</Exception>
<Environment>
<ProductName>SDL Trados Studio</ProductName>
<ProductVersion>15.0.0.0</ProductVersion>
<EntryAssemblyFileVersion>15.0.1.36320</EntryAssemblyFileVersion>
<OperatingSystem>Microsoft Windows 10 Famille</OperatingSystem>
<ServicePack>NULL</ServicePack>
<OperatingSystemLanguage>1036</OperatingSystemLanguage>
<CodePage>1252</CodePage>
<LoggedOnUser>NOSTROMO\grimwald</LoggedOnUser>
<DotNetFrameWork>4.0.30319.42000</DotNetFrameWork>
<ComputerName>NOSTROMO</ComputerName>
<ConnectedToNetwork>True</ConnectedToNetwork>
<PhysicalMemory>4093880 MB</PhysicalMemory>
</Environment>
</SDLErrorDetails>

 

All files have the same source and target language.

Any chance an SDL guru would know how to fix this?