is the preview function is the reason you are reporting this?
Yes it is.
That bit of information would have been helpful back here:
https://getmusicbee.com/forum/index.php?topic=35587.msg194606#msg194606
And it would explain why $Count functions won't work in complex virtual tags by themselves
$If($Or($Contains(<Path>,Classical)="T",$Contains(<Genre>,Classical Crossover)="T"),
$If($Or($Contains(<Keywords>,ACC)="T",
$Count(<Conductor>,<Album>)>1),
$IsNull(<Set Subtitle>,
$IsNull(<Conductor>,"• "<Sort Composer>" •","• "<Sort Composer>" "{font: Sinzano;Regular;8.25}" CON."{font: Sinzano;Regular;11}$RSplit(<Conductor>," ",1)" •"),
$IsNull(<Conductor>,"• "<Sort Composer>" ¦ "<Set Subtitle>" •","• "<Sort Composer>" "{font: Sinzano;Regular;8.25}" CON."{font: Sinzano;Regular;11}$RSplit(<Conductor>," ",1)" ¦ "<Set Subtitle>" •")),
$IsNull(<Set Subtitle>,,$If($Contains(<Set Subtitle>,Bonus Track)=T,,"• "<Set Subtitle>" •"))),
$If(<Disc Count>>1,
$IsNull(<Set Subtitle>,"• Disc "<Disc#>" •","• "<Set Subtitle>" • "{font: Sinzano;Regular;9.5}{contrast: 50}"Disc "<Disc#>{contrast: default}{font: Sinzano;Regular;11}),
$If(<Track#>>1,$IsNull(<Set Subtitle>,,"• "<Set Subtitle>" •"),)))
The $Count function has to be defined in it's own virtual tag:
CondNo. = $Count(<Conductor>,<Album>)
that then can be plugged into the other virtual tag
$If($Or($Contains(<Path>,Classical)="T",$Contains(<Genre>,Classical Crossover)="T"),
$If($Or($Contains(<Keywords>,ACC)="T",
<CondNo.>>1),
$IsNull(<Set Subtitle>,
$IsNull(<Conductor>,"• "<Sort Composer>" •","• "<Sort Composer>" "{font: Sinzano;Regular;8.25}" CON."{font: Sinzano;Regular;11}$RSplit(<Conductor>," ",1)" •"),
$IsNull(<Conductor>,"• "<Sort Composer>" ¦ "<Set Subtitle>" •","• "<Sort Composer>" "{font: Sinzano;Regular;8.25}" CON."{font: Sinzano;Regular;11}$RSplit(<Conductor>," ",1)" ¦ "<Set Subtitle>" •")),
$IsNull(<Set Subtitle>,,$If($Contains(<Set Subtitle>,Bonus Track)=T,,"• "<Set Subtitle>" •"))),
$If(<Disc Count>>1,
$IsNull(<Set Subtitle>,"• Disc "<Disc#>" •","• "<Set Subtitle>" • "{font: Sinzano;Regular;9.5}{contrast: 50}"Disc "<Disc#>{contrast: default}{font: Sinzano;Regular;11}),
$If(<Track#>>1,$IsNull(<Set Subtitle>,,"• "<Set Subtitle>" •"),)))
that allows it to work correctly.
Some of those extra virtual tags in 3.6 I'm already earmarking