Howdy,
While looking at some of the threads here I came across one mentioning the waveform seeker. I've never really used it before but it's a neat little feature so I played a bit with it and found some issues.
When I'm reading a FLAC or MP3 from my NAS, the waveform won't load and looks like this:

However if I copy the file locally, looks good!

Seems like Wacup doesn't play too well with libraries on a NAS.
This also prompted me to do some testing regarding the other issue I mentioned about ATF/metadata, so I'm going to update the other thread with this information as well.