with ‘tweak’/‘select box’/‘select lasso’ tool, when I select 2 vertices one by one, I can choose ‘merge at first’/‘merge at last’, but with ‘select circle’ tool, even my radius is 1, same operation but ‘merge at first’/‘merge at last’ did not available.
Because you are not active vertex selected simply… and idk why blender don’t have implemented this function automaticaly the last vertex selected as the active vertex… is stupid… but is like that…