CD players can be a bit picky about CD-R & to get more success with this burning it's important to use quality CD-R media and burn at a sensible speed.
Quality media is Verbatim & Taiyo Yuden. Sensible speed is 16x for Audio CDs. This slower burn rate reduces the chances of jitter which some CD players just don't like.
It's most likely that you'll have no success with these Omni discs as they are probably of a very poor quality.
These days with quality media being only slightly more expensive than the cheap c**p there's nothing to be gained by buying cheap.
You may just have to bit the bullet here & dump the Omni disks.
BTW Nero isn't the greatest app for burning Audio CDs. I'd recommend the free Burrrn (www.burrrn.net) as a better option.