Some flex sensors have two stickers (solar on one side and a Sense house logo on the other) while some just have the solar sticker. In both cases, the solar sticker is the BACK of the sensor and the non-solar side MUST face the breaker. That said, a backwards sensor likely wouldn’t manifest in what you’re seeing. Rather, it’d manifest in significant negative wattage.
As for your Tesla question, I’m 95% positive you should be able to monitor it with a single CT on either leg of the breaker. I know EVSEs often have the neutral wire, but it is not used. However, I can’t totally guarantee that. Is that how you have it currently installed?
Also Ray and @mark.kring, I’ll be sending you a message so we can help troubleshoot.