Batch Rename changed?

For many years it has been my practice to rename large groups of images in the form: xx-nn0, where xx is a Text Field containing a static numeric prefix for the entire group (enabling sequencing of groups), nn is the Sequence Number within the group, and the '0' is a Text Field that creates a numeric space between images that enables me to manually re-order images within the group.  This worked in Bridge as recently as early 2018.  This has been a powerful technique for presenting hundreds of images.

Today with Bridge 9.0.1.216 the Text Field will no longer accept numeric characters.  Why?  What is the benefit of excluding numeric characters?