NOBU "exclude files" rule not working

I would like to exclude from backup all files with xyz extension in any folder or sub-folder below the folder "abc". There are hundreds of such files in dozens of folders.

I have added the folder "C:\abc" in the section "Additional files and folders" of the settings.

I have added a rule as follows: "Exclude C:\abc\*\*.xyz"

The backup of all files under abc works fine.

The exclusion of the xyz files does not work. They are all backed up.

Norton support tells me that I have too many rules.:womanmad:  I have about 6 rules, and all the other exclude rules work, but they exclude entire folders, not files of specific extensions.

 

Can anyone confirm or deny that this functionality works?

 

Thanks,

J.