its due to some tracks having a feature lock on them, if you look at the columns next to track number and colour, there is another column to the left with a lock in it, click ctrl + ;eft click and it should disable content lock.

Yes, as Blank_Disk said, the green lock *should* save your grids even if you re-analyze the track. Unfortunately, I've found that grids sometimes still randomly reset in SSL + Bridge or in SDJ.

To resolve this and have total peace of mind, after I properly prepare a track with cue points, saved loops, manual gain adjustment (to top yellow), and grid setting, I will eject the track and find where its saved locally (command-R is the shortcut to do this easily). Then I will hit command-i (shortcut for "get info") and adjust the permissions for ALL access groups for the mp3 file to be "read-only". It's extra work and doesn't allow for on-the-fly commenting or other metadata adjustments in your Serato library afterwards, but its so nice to not worry ever worry again about this issue. (These instructions are for Mac OS, not sure how to do it in Windows.)

Let me know if you have questions.