1.11.5 - Cannot assign numeric categories on Category Sets tab

[TheNewNo2]

XnView: MP 1.11.5 - 32 bit/64 bit
OS: Windows 64bit

I have a large number of categories with numeric identifiers representing trains, for instance 378229. While these categories show up in the Categories tab, and are assignable there, they are not assignable through searching on the Category Sets tab.

Effect: This makes it much harder to work with such sets as I have to switch back and forth between Categories to create the category initially, and then my preferred view Category Sets which allows me to easily see what is assigned to the active photo. [Note, I'm new to xnview, trying to migrate away from Windows Live Photo Gallery, so maybe I'm making a mistake? I understand xnview is more powerful, but it does seem to need a lot of fettling to get it to do what were simple tasks in WLPG]

To reproduce:
1. Load the browser
2. Click to the Category Sets tab on the Preview pane
3. Enter a number such as 378229
4. Press enter

Actual behaviour (bug): Category is not assigned to photo

Expected behaviour: Category should be assigned to photo