it’s probably a ‘session’ issue… in other words i would burn whatever you want to those discs (DVD+R etc) all at once… which is just a better idea in general vs adding a file now and then adding a file to the disc at a later time.
cause take for example… if you burn a regular audio cd with say 4 tracks on it and then at a later date you add another 4 tracks… the audio player will still only see the first 4 tracks as it’s basically a session issue with standard audio players as to why it cant see the rest of the disc. (i aint sure on newer players but i know most CD players cant read the tracks added at a later date as you got to burn all of what you want on it in 1 setting.
p.s. in my opinion, i use ImgBurn to burn all my general data discs as i feel it’s the best burning software out there. (seem’s to be a favorite of alot of people on these forums to and it’s free )