The inability to detect which phenomenon led proponents of the geocentric model to logically conclude that the Earth must not be moving?

Answer

Stellar parallax

If the Earth orbited the Sun, the viewing angle to fixed stars should change throughout the year (stellar parallax), and the inability to measure this shift supported the stationary Earth conclusion for centuries.

The inability to detect which phenomenon led proponents of the geocentric model to logically conclude that the Earth must not be moving?
modelastronomystrengthWeaknessgeocentric