Mensural sign "3" - Githubissues

How, or is it possible, to display a single "3" in the mensuration sign? Here is an example where it is placed after a "C":

But there needs to be a way of showing the "3" by itself (C3 and 3 are separate things, so this is not mean a hidden C).

Example MEI data:

<?xml version="1.0" encoding="UTF-8"?>
<?xml-model href="https://music-encoding.org/schema/4.0.0/mei-all.rng" type="application/xml" schematypens="http://relaxng.org/ns/structure/1.0"?>
<?xml-model href="https://music-encoding.org/schema/4.0.0/mei-all.rng" type="application/xml" schematypens="http://purl.oclc.org/dsdl/schematron"?>
<mei xmlns="http://www.music-encoding.org/ns/mei" meiversion="4.0.0">
   <meiHead>
      <fileDesc>
         <titleStmt>
            <title />
         </titleStmt>
         <pubStmt />
      </fileDesc>
      <encodingDesc>
         <appInfo>
            <application isodate="2020-07-04T11:47:28" version="3.0.0-dev-5706f96-dirty">
               <name>Verovio</name>
               <p>Transcoded from Humdrum</p>
            </application>
         </appInfo>
      </encodingDesc>
      <workList>
         <work>
            <title />
         </work>
      </workList>
   </meiHead>
   <music>
      <body>
         <mdiv xml:id="mdiv-0000002129367227">
            <score xml:id="score-0000000509603678">
               <scoreDef xml:id="scoredef-0000000269783513" midi.bpm="400">
                  <staffGrp xml:id="staffgrp-0000001793437707">
                     <staffDef xml:id="staffdef-0000000699684333" n="1" lines="5">
                        <clef xml:id="clef-0000001448241970" shape="G" line="2" />
                        <meterSig xml:id="metersig-L2F1" unit="1" />
                        <mensur xml:id="mensur-L3F1" num="3" sign="C" />
                     </staffDef>
                  </staffGrp>
               </scoreDef>
               <section xml:id="section-L1F1">
                  <measure xml:id="measure-L1" n="1">
                     <staff xml:id="staff-0000000930171484" n="1">
                        <layer xml:id="layer-L1F1N1" n="1">
                           <note xml:id="note-L5F1" dur="1" oct="4" pname="c" accid.ges="n" />
                           <note xml:id="note-L6F1" dur="1" oct="4" pname="d" accid.ges="n" />
                           <note xml:id="note-L7F1" dur="1" oct="4" pname="e" accid.ges="n" />
                        </layer>
                     </staff>
                  </measure>
               </section>
            </score>
         </mdiv>
      </body>
   </music>
</mei>

rism-digital / verovio

Mensural sign "3" #1528