Improper visualization of some witnesses

[FLazzerini]

Sometimes certain witnesses are visualized as in apex for no reason.
An example from Lucullus:

<app from="#Luc-001-68">
                  <rdg type="lectio.sing" cause="palaeographicConfusion" wit="#S">eum</rdg>
</app>

and

 <app from="#Luc-001-69">
                  <rdg type="lectio.sing" cause="diction" wit="#A">caelerius</rdg>
</app>

Both S for enim and A for caelerius are visualized in apex:

We cannot tell by which criterion this happens. It seems to be internally consistent: both A and S are always visualized in apex. Yet it is not consistent with the coding of the other witnesses, because no such indication is given in the coding of A in the teiHeader:
<witness xml:id="A" corresp="#A.hand.1"><label>A</label>