Rockbox

Under certain circumstances the peak meter on the WPS or the Recording screen will be incorrectly displayed as solid full bars. This is a problem that I have been able to reproduce as follows:

Set the theme to Marquee (because it has peak meter displayed on the WPS during playback)

On the main menu navigate to the peak meter settings menu:
General settings -> Display -> Peak Meter

Set the scale to Linear (%)
Set the scale to Logarithmic (dB)
This causes both the minimum and maximum of range to be set to 0 dB, but don't change them yet.
The peak meter is now displayed as solid bars
With both as zero this should really show two permanently empty bars unless it clips

Next, set the minimum of range to another lower value such as -60
This should make the peak meter display normally, bouncing between -60 and 0 dB, but they remain two solid bars
To verify, return to the WPS screen and the peak meter is still displayed as two solid bars

The problem eventually seems to correct itself after 10-15 minutes, but I have not found a way to return it to a normal state through the settings. Rebooting seems to be the only way so far that I've found to correct it.