Failed to save target content

When I try to save some files as target (from xliff back to .docx) I get the following error message even though there is actually no extra tag nowhere. I ran the verification (F8) and it found no errors.

<ErrorMessage>Failed to save target content: Extra tag '<bookmarkstart id="91" name="lt_pId098">' found after segment '80'.</ErrorMessage>


-<Exception>

<Type>Sdl.FileTypeSupport.Framework.FileTypeSupportException, Sdl.FileTypeSupport.Framework.Core, Version=1.0.0.0, Culture=neutral, PublicKeyToken=c28cdb26c445c888</Type>

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