It is showing like this
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from the record view link, is it working? Record title should be single expression so you have to use concat operator to concate two value to show as a title.
From record view link also not working
Do you have the permission to access the records? You are into the viewer or administrator group of this record?
Could you please check this for me
In Line 136 Which link should i use for document viewer?
you can use documentDownloadLink to download the document and if you to preview the document then you can use dynamic link and store the value into a particular variable and use that variable to show the document as a preview.