intlinprog exitflag=0 for large-sized problem despite feasible solutions available

Hi

I am working on a problem that uses binary decision variables to find an optimal solution using intlinprog. I have managed to solve smaller-sized problems. The solver goes into the branch and bound stage and finds a handful of feasible solutions, converging to the optimal solution. However, I am having issues with larger-sized problems where the solver gets stuck at a node for a very long time and eventually gives the exitflag of 0 (no feasible solution found). This should not be the case, because the way the indices are structured there must always be a few feasible solutions available.

The problem deals with binary decision variables, and the value that is minimised in the problem (time) is retrieved from a predefined list of integer values. I have tried to relax the problem with the following options:

options = optimoptions('intlinprog',... 'BranchRule','mostfractional',... 'ConstraintTolerance',1e-3,... 'CutGeneration','none',... 'CutMaxIterations',10,... 'Heuristics','rss',... 'HeuristicsMaxNodes',Inf,... 'IntegerPreprocess','advanced',... 'IntegerTolerance',1e-3,... 'LPMaxIterations',Inf,... 'LPOptimalityTolerance',1e-1,... 'MaxNodes',Inf,... 'MaxTime',172800,...); 'NodeSelection','minobj',... 'ObjectiveImprovementThreshold',1,... 'RelativeGapTolerance',1,... 'RootLPAlgorithm','primal-simplex',... 'RootLPMaxIterations',Inf);

Please try to advise what I could do next. I think my only option now is to deactivate Integer Preprocessing, but this will greatly increase my runtime (Edit: I have tried this, as well as setting 'LPPreprocess' to 'none' - still no feasible solutions found). I am using MATLAB 2016a. Any help would be very much appreciated.

Regards, Enrico