Contradiction with Genesis 49:10
Deuteronomy 33:6 blesses the tribe of Reuben, but Genesis 49:10 focuses on the preeminence of the tribe of Judah over Reuben.
Genesis 49:10: The sceptre shall not depart from Judah, nor a lawgiver from between his feet, until Shiloh come; and unto him [shall] the gathering of the people [be].
Contradiction with Numbers 16:1-3
While Deuteronomy 33:6 seeks well-being for Reuben, Numbers 16:1-3 recounts rebellion led by Korah, a descendant of Reuben, against Moses.
Numbers 16:1-3: Now Korah, the son of Izhar, the son of Kohath, the son of Levi, and Dathan and Abiram, the sons of Eliab, and On, the son of Peleth, sons of Reuben, took [men]:
Contradiction with 1 Chronicles 5:1
Deuteronomy 33:6 blesses Reuben, but 1 Chronicles 5:1 notes that Reuben lost his birthright due to sin with his father's concubine.
1 Chronicles 5:1: Now the sons of Reuben the firstborn of Israel, (for he [was] the firstborn; but, forasmuch as he defiled his father's bed, his birthright was given unto the sons of Joseph the son of Israel: and the genealogy is not to be reckoned after the birthright.
Contradiction with Genesis 35:22
Deuteronomy 33:6 offers a positive outlook for Reuben, yet Genesis 35:22 records Reuben's sin which resulted in his loss of the birthright in later narratives.
Genesis 35:22: And it came to pass, when Israel dwelt in that land, that Reuben went and lay with Bilhah his father's concubine: and Israel heard [it]. Now the sons of Jacob were twelve:
Contradiction with Hosea 5:10
Deuteronomy 33:6 hopes for preservation and life for Reuben while Hosea 5:10 accuses the princes of Judah of stealing, hinting at judgment which can be seen as correlating with Reuben's loss of position.
Hosea 5:10: The princes of Judah were like them that remove the bound: [therefore] I will pour out my wrath upon them like water.
Paradox #1
Deuteronomy 33:6 mentions a blessing for the tribe of Reuben to live and not die and to have numerous people. However, historically, the tribe of Reuben became less prominent and smaller in population, eventually being among the first tribes conquered and displaced, which could be seen as inconsistent with the idea of them thriving and growing.