My solution: try to reinstall again the R1, and make a full wipe before.
Does anybody facing freezing issues with f2fs?
I have this problem, it happens sometimes while browsing. Just sleep button works and after 10 seconds tablet wakes up. Tried with _that kernel and grimlock, happened in both.
I don't have any problem like this on ext4
I also saw people having this problem in katkiss rom on android 4.4 and 5.0