Hi Avi,
This issue seems to be fixed in the new Corona 12 DB.
It's not fixed using current DB here, but it behaves differently using Max 2024, maybe you used that one for testing:
Try to close the material editor before opening the example file and disable material editor rendering. Then load file, start rendering and you get the warning message. Then: open material editor, activate material rendering, make sure you see the swatches of the triplanar input nodes and zoom a bit in and out. The material previews get updated and the warning message is gone when starting to render from now on.
Using Max 2023 and current daily behaves exactly like lupaz showed it.
Good Luck