Bug - Sort by the number of episodes (Plan to watch)

Hey, I noticed a bug while sorting episodes by their numbers.

Instead of being sorted correctly, some dramas weren't in the right order. For example, the first 33 were either descending or ascending properly, but after that, a drama with no confirmed number of episodes (?) is listed. Following that, the number of episodes became random: ? 38 48 ? 10 ? and so on.

I checked to see if it's only a problem on my account, but it doesn't seem that way.