There is a glitch that I found. I moderate a game called Hill Climb Racing 2 and before I was a moderator, the other moderators made the timing for in game time and didn’t fill out the main time. Then, it got changed to remove the in game time. I verified a run and saw that the older run with only in game time still shows the time but it shows that they are below the newer run when it should be above.

This sound incredibly vague, but this usually isn't a glitch, it depends on how you set up your default timing method (which you can see by going to edit game -> info).

If your default timing method is real time, then games with only in game time will be at the bottom, even if they have faster in game times than some other runs that have both in game time and real time.

If you are sorting runs by real time, then it makes sense that runs without real time entered will be at the bottom of the list.