I have read previous posts with not much hope.
In Logos 5, is there a way to selectively clear a certain tag from a lot of resources at one time without having to clear all the tags?
I think your lack of hope in this instance is well placed. Kind of like the game of pickup-sticks: pulling out the perfect stick without collapsing the pile is do-able but only 1 by 1.
Us 'taggers' have to sign a Logos acknowledgement form that using multiple tags will generate this problem. Somehow you didn't sign the form. Now look what has happened? (Just joking.)
Not possible, but it is a feature that has been requested. Please go vote for it over on the Logos UserVoice forum. The more people want this, the more likely Logos will be to implement it.
