Re: create a simple frame
It's extraordinary.
Oscillograms would help a lot. A lot.
Anyway, Can you provide a Canny's diagram, Nextion project, your logic converter product page link/docs, and your wiring diagram with ALL connections of ALL devices include ALL signal and ALL power connections, please? We will try to reproduce your situation in our lab. You may be sure, we will provide a solution or will replace your hardware after all.
I point out that this is the same wiring and the same program.
Also, please provide the CannyLab Main menu->Device->Information screenshots for each controller.
But before all: if you use logic converter without internal pull-ups, you need to setup Pulled-up UART configuration for CANNY 7