I think you are correct, it is Enable active high and the SEN/STA goes low for clear to send. I did manage to destroy a TH3122 myself and it had those symptoms, plus heating up very fast. I think that I would be setting the TH3122 up on its own and see what is happening "bareback".
What are you going to do with your board?
If you want to send me a PM, I can share my circuit diagram etc with you. I now have fully working Melexis and MCP version prototypes. I am just refining the software a little now before committing to PCB manufacture.