I need the site url tand or a screenshot o see what you are seeing
“slp_Filter undefined “is to ubiquitous a term for me to figure out what or where exactly you may be seeing that.
(this url is not view able thttps://ilffp.local/)
please provide a screenshot since I do know what you mean by “single location page” nor what error you are seeing, nor where you are seeing it.
are you referring to the back end locations or SEO Pages, or the website page link that directs to SEO Pages>?? front end? Browser? SEO Page template?
have you tried a vanilla WordPress theme? What theme are you using?
Example: Are you using Enfold Theme with SEO Pages, (there is info here on that)