Option Values with problematic Values
I believe we solved this. The option group in question is a multiple choice integer (radio buttons) with values 0, 1, and 2 representing "No", "Yes",and "Retest". Nulls are allowed. All values in the table matched. Other than the warning, we never experienced any issues.

We noticed that standard Yes/No option groups used 0 and 1 values, but other multiple choice integer option groups used non-zero positive  integers. We reset all of our "No" records to value 3 and changed the Option Group to match. The warning immediately stopped.