What were the problems with the theory of continental drift?
The theory contradicted existing theories and had no mechanism
The theory of continental drift contradicted the prevailing theory of geosynclines. The geosyncline theory was used to explain how continents, sedimentary layers, and mountains were formed. The scientific community was invested in the geosyncline theory so rejected the Continental drift theory.
The theory of continental drift contradicted the prevailing theory of uniformtariaism. The idea of slow uniform geological processes was and is firmly entrenched in the scientific community. As first proposed the Continental Drift theory proposed rapid and recent massive movement of the Continents. The theory of Continental Drift was modified and renamed as Plate tectonics to remove the idea of rapid and recent movements, in order to be accepted.
The theory of continental drift contradicted the timeline of Darwinian evolution that existed at the time the theory of Continental Drift was proposed. Gaylord Simpson a prominent evolutionary scientist opposed Plate Tectonics up through the 1970s. The timelines of both evolutionary theory and plate tectonics had to be adjusted to bring the two theories into agreement.
A continuing problem with Continental drift and its modern form is how to explain the thick level layers of sedimentary layers on the continents. Deep ocean sediments are destroyed at converging boundaries and subduction zones. There is no mechanism for how the deep ocean layers end up in horizontal strata on the continents.
The problem that was used to reject Continental Drift is that the theory had no mechanism or explanation for what could cause the movement of the massive continents.