I'm using ArcGIS Pro 2.4.3
I'm using the interactive Definition Query window as shown in the attached.
'Congo, Dem Rep of the' is not added correctly to the SQL string.
Below is the result in the SQL window The interactive window is incorrectly parsing 'Congo, Dem Rep of the' into two pieces.
COUNTRY_NA IN ('Angola', 'Congo', 'Dem Rep of the', 'Malawi', 'Tanzania', 'Zimbabwe', 'Mozambique', 'Congo', 'Dem Rep of the', 'Botswana', 'Namibia')
These data are from the US Department of State. http://geonode.state.gov/layers/geonode%3AGlobal_LSIB_Polygons_Detailed