Troubleshoot time:
-Check pH of water and soil runoff
-Are leaves soggy?
Any evidence of botrytis in branches or on the plant? Soggy or Browning leaves, branches, etc.
-heat stress?
Check tent temperature, medium temperature, water temperature.
-Root rot or rootbound?
Check roots, moisture of soil medium
-Advanced nutrient burn?
That's all I can think of based off of your pictures. I hope this helps.