Well, you are not alone. Just installed a new PinSound+ in my Doctor Who and am seeing the same issue with some of the mixes.
Actually deleted the 'Doctorin' The Tardis' mix after reading this, but that did not actually resolve the problem. If I leave a mix selected, it appears to behave but if I try to select a different mix (running the volume to zero) it will not change the selected mix and if I try it again it triggers the 'scanning USB' message. I seem to be 'stuck' on the "modern" mix at the moment.
Don't suspect USB drive speed as this is a USB 3.0 device that came with the kit. I have noticed that if I take the USB drive to my PC following the 'scanning USB' prompt it will indicate that there is an error on the drive and offer to scan/repair it (Windows 10), but if I let it do so it reports "no error found" following the scan. Not sure what's up with that.
Also seems that levels on the voice callouts in the mix seem quite low compared to the music tracks. Trying to see if I can level that out through the equalizer settings.
