Hi and welcome to the forum
Playback problems often are due to a bad burning. Sometimes a standalone refuse to play some media because it's programmed in firmware (aka locked) to refuse that media.
Usually (not always) this issue can be solved using best quality media. Also changing booktype of +R media in ROM can solve compatibility issues.
Sometimes it's related to a dirty/scratched media. Some drives are better more than other to read scratched media.
Sometimes, moreover, it can be related to a dirty optical pickup of the standalone.
Or a combination of the above. :bigsmile: