Okay, two problems (which may end up being related)...
1) Some songs won't analyse.
What is the file format of those songs? MP3 / M4A / AIFF / WAV / AAC / FLAC / video? Where are they located? Is the path + filename longer than 256 characters? Does the filename contain any non-English characters?
2) Some songs won't export.
Have you looked in the logs to figure out which songs they are? You'll find the log files in your /Documents/rekordbox folder. You can copy/paste two or three lines here so I can look at them to see what it might be.