Link to anchors in 'reference' page not working

I use pages with the ‘reference’ block, so that I can browse by a specific property.

I have noticed that the link of the letters in the skiplink tab are not working, i.e. the page does not jump to the anchored letter when the user clicks on a letter.

Under further inspection I noticed that this happens because the ID assigned to the anchor itself is a capital letter (e.g. id="A") whilst the link of the skiplink letter points to a lower-case letter (<a href="#a">A</a>). This is enough to invalidate the link.

A live example is here.

Is this related to these lines?