Incorrect Track Number being passed to control point

[simbun]

For a minute there I thought 'DiscNumber:nil' might be the answer, but then it prevents DISCSUBTITLE from showing for those that do exist.

Following the DiscNumber:nil logic I tried something similar with TrackNumber; I set 'TrackNumber:inTN' in aliasTags, put 'inTN' into itemTags and added 'Title.displayFormat={$inTN^^^$title^. ^^}' to tagFormat, which all works, except it doesn't sort by it. Is there any way to sort Title by the tagFormat value?