See links below - it's Revit 2018 - Why are we all still having to hack section and callout heads to enable them to mask stuff behind by using underscore text to represent the middle line? The root cause here seems to be that the ability to Send To Front/Back does not exist in these families (so the masking region always hides the middle line regardless of order of creation), and the Masking Regions insist on rotating with the section head (so using half-circle two masking regions won't work because the line tends to rotate instead of stay horizontal).
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