Content files that are labeled with both text and numeric values sort correctly, but files containing only numbers, don't share this behavior and end up with weird sorting order.
MyMat_20, MyMat_201 etc. work correctly while "20", "201", "210" dont sort numerically.
Create new content files in the Content Browser and label them as
You will immediately see the ordering is non-numeric.
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-26544 in the post.