The US Embassy explained that it will prioritize " ... services to US Citizens, including applications for passports, Consular Reports of Birth Abroad, Immigrant Visa cases that are pending in the Consular Section and Emergency Nonimmigrant Visa services.
From a statement issued by the US Embassy In Nicaragua
Effective Wednesday, May 16, 2018, and until further notice, U.S. Embassy Managua will be unable to process routine nonimmigrant visa applications. The unstable security conditions in Nicaragua have reduced the hours the Embassy is open to the public.
Consular staff will prioritize U.S. citizen services including U.S. passport applications and Consular Reports of Birth Abroad, immigrant visa cases already pending at the Embassy, and emergency nonimmigrant visa services. Emergency visa cases only include travelers with urgent medical circumstances, students and exchange visitors with imminent report dates for programs, and urgent business travel.
All nonimmigrant visa appointments that were not expedited have been canceled and the application by courier program for visa renewals and minors with two visaed parents is no longer available at this time. Nonimmigrant visa applicants who do not meet the criteria for an emergency appointment may apply in any other country where they are physically present, including neighboring Central American countries, but should bear in mind that they must demonstrate strong ties to their home country and the intention to return after a short stay in the United States
It is also important to note that visa application fees paid in Nicaragua cannot be transferred for use in another country. Fees already paid to the U.S. Embassy in Managua are not refundable, but are valid for one year from the date of payment for possible future use in Nicaragua when the Embassy reopens for routine visa services.