When adding or configuring a custom column via the "Manage Custom Columns" dialog while releases with matched tracks are already loaded in the Album view:

• The cells in the custom column render with a solid white background across track rows where no value is present.
• Built-in columns (such as "Disc Subtitle") on the exact same rows do not show a solid white background when empty, remaining visually consistent with the row's background tint (e.g. match quality similarity tint).

This leaves a noticeable solid white vertical band down the custom column. The solid white background persists until the release is reloaded or Picard is restarted.

Steps to Reproduce

1. Load a release with matched tracks into the Album view.
2. Right-click header > Manage custom columns…
3. Create a custom column (e.g. for disambiguation) and add it to the Album view.
4. Observe the newly rendered custom column cells on tracks without a value.

Expected Result

Empty custom column cells should have a background consistent with the rest of the row, matching the behavior of empty built-in columns like "Disc Subtitle".

Actual Result

The custom column cells render with an opaque white background, contrasting against the tinted background of adjacent cells in the same row.