There were some CD-r's from TDK's and Philips that has problems to read in a CD32.
The problem is that they buy CD-r's from different suppliers. Even a spindle of Cd-r's could be different.
Using Platium CD-r's will also work, but if you always want one supplier with the same quality, you could better buy Verbatim or even Traxdata CD-r's.