I am working on an MIP whose continuous variables I want to make integer. With continuous variables I obtain an optimal solution and most (all but 2) of those variables are actually integers, even though they are continuous. I wanted to force the solution to be integer, so I made them positive integer variables with a suitable upper bound, but running the model this way makes it unfeasible. I see no restrictions that might create this unfeasibility, only an equality, but this equality is a sum of integer variables is an integer, which shouldn’t cause any trouble.