E-1 Visa

The U.S. State Department is launching a pilot program to pre-screen E-1/E-2 visa applicants at consular posts in Canada. Kentucky Consular Center officials will contact the E-1/E-2 applicant's U.S. employer to verify information about the application, including the legitimacy of the company and the investment. This prescreening aims to assist consular officers to focus on the individual applicant's qualifications. The State Department hopes to implement the pilot around the world at consular posts that process E visa applications.

What kind of problems can employment-based nonimmigrants (H-1, L-1, E-1, E-2, E-3, TN) face during reentry?

I think this question is most relevant for H-1 holders, but other employment-based nonimmigrants may also note the general principles here.