This issue will likely appear if Creo cannot find the Material folder used by the Ansys Solver.
Can you please check if you see the MaterialLibrary folder under the following location?
When you assign a material to a model and run the analysis, it will be syc'd in this folder. You would just use your regular materials as you would normally do. If that folder does exist, delete it and then start Creo again and give it a try. This will recreate the MaterialFolder automatically.
This is not likely to do with your graphics card. If it was an issue, you would not have been able to start the analysis.
If that is still an issue, let me know and we can jump on a teleconference to sort it out.
BTW....are you using the build from ptc.com or from this group? I updated the build in the group to the production version of Creo 126.96.36.199 which contains the early access version of Creo Simulation Live.