"Index was out of range" error when preparing a RoboHelp TOC xlf file

Getting the Error Message "Index out of range. Must be non-negative and less than the size of the collection. Parameter name: index". The file is a TOC (Table of Content) .xlf file generated by Adobe RoboHelp.

The sdl error file content is:

<SDLErrorDetails time="3/14/2022 9:31:27 AM">
<ErrorMessage>Index was out of range. Must be non-negative and less than the size of the collection.
Parameter name: index</ErrorMessage>
<Exception>
<Type>System.ArgumentOutOfRangeException, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</Type>
<ParamName>index</ParamName>
<HelpLink />
<Source>mscorlib</Source>
<HResult>-2146233086</HResult>
<StackTrace><![CDATA[ at System.ThrowHelper.ThrowArgumentOutOfRangeException(ExceptionArgument argument, ExceptionResource resource)
at Sdl.FileTypeSupport.Filters.Xliff.Infrastructure.MarkupBuilders.BuilderHelpers.Segment.MatchHelper.HasElementsBetweenSegments(Int32 previousSegmentPosition, Int32 currentSegmentIndex, List`1 paragraph)
at Sdl.FileTypeSupport.Filters.Xliff.Infrastructure.MarkupBuilders.BuilderHelpers.Segment.MatchHelper.MatchParagraphElements(ContainersContext containerContext)
at Sdl.FileTypeSupport.Filters.Xliff.Infrastructure.MarkupBuilders.SegmentBuilder.CheckSegmentsAndMatch(IMetaDataContainer container)
at Sdl.FileTypeSupport.Filters.Xliff.Infrastructure.MarkupBuilders.MarkupBuilderBase.ProcessCurrentParagraphUnit()
at Sdl.FileTypeSupport.Filters.Xliff.Infrastructure.MarkupBuilders.MarkupBuilderBase.OutputParagraphUnit()
at Sdl.FileTypeSupport.Filters.Xliff.Infrastructure.Consumers.AttributesConsumers.TranslateAttributeConsumer.Consume(XmlNodeParsed message)
at lambda_method(Closure , IMessage )
at Sdl.FileTypeSupport.Filters.Xliff.Infrastructure.InMemoryBus.Publish(IMessage message)
at Sdl.FileTypeSupport.Filters.Xliff.Extractor.ParserImpl.Publish(XmlNodeParsed message)
at Sdl.FileTypeSupport.Filters.Xliff.Infrastructure.XmlParser.Parse(XmlTextReader reader)
at Sdl.FileTypeSupport.Filters.Xliff.Extractor.ParserImpl.Parse(String xliffPath)
at Sdl.FileTypeSupport.Filters.Xliff.Parser.ParseNext()
at Sdl.FileTypeSupport.Framework.Integration.FileExtractor.ParseNext()
at Sdl.FileTypeSupport.Framework.Integration.MultiFileConverter.ParseNext()
at Sdl.FileTypeSupport.Framework.Integration.MultiFileConverter.Parse()
at Sdl.ProjectApi.AutomaticTasks.Conversion.ConversionTask.ProcessFile(IExecutingTaskFile executingTaskFile)
at Sdl.ProjectApi.AutomaticTasks.AbstractFileLevelAutomaticTaskImplementation.Execute()]]></StackTrace>
</Exception>
<Environment>
<ProductName>Trados Studio</ProductName>
<ProductVersion>Studio16</ProductVersion>
<EntryAssemblyFileVersion>16.2.9.9198</EntryAssemblyFileVersion>
<OperatingSystem>Microsoft Windows 11 Pro</OperatingSystem>
<ServicePack>NULL</ServicePack>
<OperatingSystemLanguage>1033</OperatingSystemLanguage>
<CodePage>1252</CodePage>
<LoggedOnUser>LAPTOP-6ALSMCG8\HP</LoggedOnUser>
<DotNetFrameWork>4.0.30319.42000</DotNetFrameWork>
<ComputerName>LAPTOP-6ALSMCG8</ComputerName>
<ConnectedToNetwork>True</ConnectedToNetwork>
<PhysicalMemory>16559604 MB</PhysicalMemory>
</Environment>
</SDLErrorDetails> 



Just moved the error text into a code box for readability
[edited by: Paul at 10:28 PM (GMT 0) on 14 Mar 2022]
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