Output window of IntelliJ IDEA cuts output
Couldn't get more votes to close the question so I have to answer it myself.
IDEA_HOME\bin\idea.properties
#-----------------------------------------------------------------------
# This option controls console cyclic buffer: keeps the console output size not higher than the specified buffer size (Kb). Older lines are deleted.
# In order to disable cycle buffer use idea.cycle.buffer.size=disabled
idea.cycle.buffer.size=1024
Preferences/Settings -> Editor -> General -> Console
, check the box next to Override console cycle buffer size
, set to a larger number than 1024 KB.