Can you upload the log here as well. I see the error in my log but only if I don’t have any hookups for the A or B input to the material. The log should include some of the issue that is happening and where to actually look to start resolving this.
You’ve also got what looks to be a more complex material setup here using different blend modes and whatnot based on the inputs available on the Material Attributes node. I would be really helpful to see the full material setup or have sample project that demonstrates this easily. If needed you can share privately but this is up to you ultimately.