What context are you using the new scope attr in? Both of those statements will use a new line in the resulting value, which you can see if you test it in a Script connector for example:

<arc:set attr="encodedurl" value="http://someurl/" />
<arc:set attr="expiry" value="2020-01-01" />

<arc:set attr="scope">;encodedurl]\nnexpiry]</arc:set>
<arc:throw code="x" desc=""scope]" />

You can see the line break in the thrown exception:

And in the second case, you get the preceding and following line breaks:

<arc:set attr="encodedurl" value="http://someurl/" />
<arc:set attr="expiry" value="2020-01-01" />

<arc:set attr="scope">
   encodedurl]
   expiry]
</arc:set>
<arc:throw code="x" desc=""scope]" />

Of course, the context from which scope is evaluated is important here, because the exception here supports multiline data. 

I’m using the scope and encoding it using HMACs.

I then pass it in the message header to a REST connector and use it in a HTTP Header

The REST Connector log shows these two headers being evaluated correctly.

Very similar to https://arc.cdata.com/kb/articles/arc-http-signature-auth.rst

Here’s my script

<arc:set attr="encIn0.data" value=""url]" />
<arc:set attr="encIn0.format" value="URL" />
<arc:call op="encEncode" in="encIn2" out="result0">
  <!-- setting the output file data to be the encoded data returned from the operation -->
  <arc:set attr="output.encodedurl">dresult0.encodeddata]</arc:set>
</arc:call>



<arc:set attr="fixedtimestamp" value="03-02-2024"/>
<arc:set attr="expiry">pfixedtimestamp| todate('dd-MM-yyyy','U') |dateadd('day', 7)|datediff('second', '1970-01-01 00:00:00Z')]</arc:set>
<arc:set attr="scope">coutput.encodedurl]\ndexpiry]</arc:set>

<arc:set attr="encIn.data" value=""scope]" />
<arc:set attr="encIn.format" value="HMAC" />
<arc:set attr="encIn.hmackey" value=""azureprimary.key]" />
<arc:set attr="encIn.hmacalgorithm" value="SHA" />
<arc:set attr="encIn.hmacbits" value="256" />
<arc:set attr="encIn.outformat" value="BASE64" />
<arc:call op="encEncode" in="encIn" out="result">
  <!-- setting the output file data to be the encoded data returned from the operation -->
  <arc:set attr="output.hashb64">hresult.encodeddata]</arc:set>
</arc:call>


<arc:set attr="encIn2.data" value=""output.hashb64]" />
<arc:set attr="encIn2.format" value="URL" />
<arc:call op="encEncode" in="encIn2" out="result2">
  <!-- setting the output file data to be the encoded data returned from the operation -->
  <arc:set attr="output.signatureUrlEncoded">oresult2.encodeddata]</arc:set>
</arc:call>


<arc:set attr="sigheader">SharedAccessSignature sig=toutput.signatureUrlEncoded]&se=]expiry]&skn=sas-tracking-events-topic&sr=coutput.encodedurl]</arc:set>
<arc:set attr="outfile.FilePath" value=""FilePath]" />

<!-- debug -->
<arc:set attr="outfile.Header:expiry">pexpiry]</arc:set>
<arc:set attr="outfile.Header:scope">cscope]</arc:set>
<arc:set attr="outfile.Header:signature">toutput.hashb64]</arc:set>
<!-- debug end-->

<arc:set attr="outfile.Header:sigheader" value=""sigheader]" />
<arc:set attr="outfile.Header:brokerProperties">{"SessionId":"sguid()]"}</arc:set>

<arc:push item="outfile" />

The issues is with 

<arc:set attr="encIn0.data" value=""url]" />
<arc:set attr="encIn0.format" value="URL" />
<arc:call op="encEncode" in="encIn0" out="result0">
  <!-- setting the output file data to be the encoded data returned from the operation -->
  <arc:set attr="output.encodedurl">gresult0.encodeddata]</arc:set>
</arc:call>

It’s encode //:, = etc to lowercase (%2f, %3d etc).  I’m comparing this with Postman and Crypto JS which encodes to uppercase (and works)

All solved and working now