"In the nineteenth century it was claimed, in all seriousness, that Columbus's contemporaries thought the world was flat and expected him to sail over the edge. This story is balderdash. But the fact that everyone (or at least every properly educated person) thought that you could in principle sail around the world (and in 1519-22 Magellan did just that) does not mean that they thought it was round."
David Wootton, The invention of science: a new history of the scientific revolution (New York: HarperCollins Publishers, 2015), 111. Wootton outlines the five available theories (111-117), of which only the fifth ("held by Robert Grosseteste (c. 1175-1253), Andalo di Negro (1260-1334), Themo Judaei (mid fourteenth century) and Marsilius of Inghen (1340-96)") corresponds to the "the modern conception" of "'the terraqueous globe'" (117). Yet "this last belief found no support in the fifteenth century", and was only rehabilitated in the wake of the Columbian discovery of 1492. The first of the five, that of Sacrobosco (c. 1195-c. 1256), is represented by the illustration, taken from p. 119 of a 1585 printing of Christophorus Clavius' In sphaeram Ioannis de Sacro Bosco commentarius (Wootton reproduces this from the 2nd edition of 1581), where it is rejected (124).
For an earlier critique of Wootton on this (who, however, seems to rise to it here), go here.