The passuk (18.22) makes no sense to say that, "HaShem stood before Avraham" as the verb omed is used. (One must ask one's self, 'Why would HaShem have a need to stand before Avraham?' The answer is only except to see and know for sure) For example, when the Torah tells us that the Daughters of Zelophehad stood before Moshe (Moses) to decide a court case (inheritance) it uses the word וַתַּעֲמֹדְנָה.
The Hebrew verb omed is used to convey the idea that a person is providing court testimony (hence the translation, "standing") before either God or an authority figure such as Moshe.
The passuk (verse) in question should not be read in isolation but rather read together with the rest of the sidra (passage):
For example 18.21 says "I will go down ..., etc.."
With HaShem "there is no place G-D is not" (G-D is everywhere) so with G-D there is no "going down or standing or sitting"; these are merely anthropomorphisms used to convey a particular idea. In the words of our Sages, "the Torah speaks in the language of men."
In our passage, the Torah is telling us G-D humbles Himself ("I will go down and see ... and if not I will know.") by getting involved in the affairs of mankind. The idea being conveyed by the Torah is that of a court case: We begin our sidra in passuk 18.1 Veyyera - "And the L-RD appeared to him...."
Maimonides explains that 18.22 must be read in the context that Avraham has begun a prophetic vision (18.1), for we read in 18.25 "shall not the Judge of all the Earth do justly?" and in 18.33 we read, "And the L-RD went His way, as soon as he had left off talking with Avraham... and Avraham returned to his place."
Since G-D is everywhere; 'Where could HaShem go?' and where did Avinu Avraham return to? Obviously, Avraham returned to his tent. Yet after the destruction of S'dom and Gehmorrah, we read in 19.27 "And Avraham got up early in the morning to the place where he had stood before the L-RD." So, according to Rabbi Yishmael's Rules of Interpretation (Gezeera Shava) 19.27 comes to clarify 18.22.
According to the blog: <https://truthonlybible.com/2018/02/03/the-tiqqune-sopherim-emendations-or-glosses/> The Tiqqune Sopherim does not list B'rashith (Genesis) 19.27 as an emendation so the correction of 18.22 make perfect sense when reading the entire passage of where HaShem appeared to Avraham! (At the Terebinth of Mamre....)
Although rabbinic lists vary, the main lists have eighteen verses with alleged emendations, as shown below, with McCarthy’s evaluation of the authenticity of each tradition (in Carmel McCarthy, The Tiqqune Sopherim and Other Theological Emendations in the Masoretic Text of the Old Testament, Orbis Biblicus et Orientalis 36 [Göttingen: Vandenhoeck & Ruprecht, 1981], 61-129).
Genesis 18:22—”Yahweh was still standing before Abraham” (וְיהוה עוֹדֶנּוּ עֹמֵד לִפְנֵי אַבְרָהָם) was changed to “Abraham was still standing before Yahweh” (וְאַבְרָהָם עוֹדֶנּוּ עֹמֵד לִפְנֵי יהוה), because to “stand before” someone usually means to minister to an authority who is sitting. McCarthy: unauthentic emendation
Reading the Tiqqune Soferim for 18.22 makes more sense when one sees that the Superior HaShem consults with the inferior Avraham!