I'm writing a bug report, at first I thought the bug happened all the time but now I realize that occasionally it works correctly.
I was going to say that the bug was sporadic, but actually, that would imply that most of the time it worked and the bug was occasional, which is the opposite of what I mean.
Is there a word which is like sporadic but means happens frequently but not all the time? Or should I just flip the sentance and say that it sporadically works.