If I remember right the limit should be 60,000 lines at this point not 6,000. The limit is just there because we had an issue where someone opened a 500,000 (or something crazy like that) line file on a computer that didn’t have enough ram to render the whole file so the computer stopped responding, then every time GC was opened it would lock up the computer so he couldn’t select a different file to open. Maybe the limit should be a setting so you could up it if you needed to?
In either case, the limit applies only to how many lines are shown in the preview, I wouldn’t expect it to affect how the file cuts. If you had the log file that would be awesome, but if not the .nc file would be really helpful if you are willing to share it