There appears to be a glitch with the convert and delete function of the program.
If you select a list of files to convert it will convert the first item in the queue, and the load the converted item file to the last position in the queue. It will then delete the converted item and remove from the queue it will then mark the 1st item in the list (which was previously the 2nd item) with the comment Source file deleted, converted file loaded. This results in only 50% of the files being converted.
For example queue of:
track 1.wma
track 2.wma
track 3.m4a
track 4.m4a
track 5.wma
track 6.wma
After conversion to mp3 will show
track2.wma Source file deleted, converted file loaded.
track4.m4a Source file deleted, converted file loaded.
track6.wma Source file deleted, converted file loaded.
track1.mp3
track3.mp3
track5.mp3
One workaround would be to load each item you want to convert into the list 2x and sort by name, this will make each item show up 2x each one right after the other... It will convert the first and skip the second... I've submitted a bug fix, so we'll see how long it takes to hear back... It should be a pretty quick fix, however they may decide it's not high on the priority list, or they may want to fix several things before they release the next update.