Hi @chucksta,
Have you checked whether the content of your Email Body output matches the type of the field corresponding to the SP list?
The Email Body output is generally in Html format, you need to convert it to Text format.
I have made a test on my side and the flow works well. Please take a try with the following workaround:
Image reference:

The flow works successfully as below:

Please take a try and let me know if issue still exist.
Best Regards,
Barry