Gospel Library - Spacing Not Working

I am having a problem setting the spacing in Gospel Library.

Gospel Library (Latest)
Ipad running 4.3.5 (also occurs on 4.3.0)

Open settings in Gospel Library, Click 'Fonts, Spacing, Alignment', then click 'Spacing'.

Move slider to change spacing to ~25%, click settings, then done. Notice spacing is then set to 0.

If you set spacing to ~60% then it seems to work, otherwise it always reverts to 0.

I see the same issue on my iPhone 3G running Gospel Library v2.3.0 and iOS 4.2.1.