Misting nozzles are small, so they clog easily. A clogged nozzle means some roots get no solution, and those roots can dry out.
Filter the solution
Use a fine filter on the pump intake to catch debris before it reaches the nozzles.
Check the spray
Watch each nozzle during a cycle. An uneven or weak spray is an early sign of a blockage.
Clean regularly
Remove and rinse nozzles on a schedule. Use clean water, and never use anything that could damage the nozzle or leave residue.