With our latest 525G deployment, we have seen the following.
If you specify a gap in the speed-dial command between buttons, the gap button shows a blank speed-dial
speed-dial 1 324 label "324"
speed-dial 3 123 label "123"
When looking at the phone, button #1 correctly shows ephone-dn 1 assignment, button 2 shows speed dial 324 and button 4 shows speed dial 123. The problem is that button 3 shows the speed-dial icon, but no label. Luckily, pressing the button does nothing, but it is very odd.