Excellent facts for us to go on. We all want to get to the bottom of this. We are studying the Plextor drive models you have to see if there may be a wrong definition structure for them that might cause this.
The code we are using is new to us from a reputable vendor. All drives that are "claimed" to be supported have been "assumed" to already be proven. However, I'm beginning to question that.
The question yet to be determined is what is causing this and how to fix it.