I’ll start. Obi-Wan doesn’t remember owning R2 in the OT yet owns him in the prequels.
I never had a problem with this from either the PT or OT perspective. Obi-wan holds his cards close to his chest and has no problem leaving out vital details of Luke’s relation to Darth Vader, so it’s totally in character for him to conceal recognition of R2 and C-3PO. He doesn’t lie, after all; he only says he doesn’t remember owning any droids, not “I’ve never seen that droid in my life.”