In construction, what are the usual problems that you' are facing as a Construction Manager?

Site possession (on major projects), Contractor's performance, procurement, discrepancies between user requirements and working drawings and contractual discrepancies etc.. 

Usually in Construction, project's are problematic  at the start because of setting up offices, Material Management and similarly unfinished snag are always problematic. It is always better to have estimated material within stores through calculating by dint of drawing, if sudden shortage, it may be procured from the local market.