Daniel,

           I am confused by your statement "edited the label," as labels are created and assigned to using filters, which are what get edited.   I just created a label under Gmail named NVDA Group Messages.  I then created a filter on subject that has one thing in it:  [nvda].  (open square bracket, lower case nvda, close square bracket) coupled with Does not have: Private.  I do not want messages sent to me as private messages to be grouped in with NVDA group messages.

           The actions are Skip inbox (archive it) and Apply label NVDA Group Messages.   If you want it to apply to email messages you've already received, then you also need to check the checkbox for Also apply filter to matching conversations, otherwise it will be run only on new messages as they arrive.

            It works like a charm.
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Brian - Windows 10 Pro, 64-Bit, Version 2004, Build 19041  

A gentleman is one who never hurts anyone's feelings unintentionally.

          ~ Oscar Wilde