Bug or Feature? - transmuting cards

Hi there,
actually I am not really sure if this is a bug or a feature, therefore no post in the bug megathread:
while viewing my cards with an active filter for "only standard" the transmute function is disabled? the button is missing. is this on purpose? and if so... why?^^
I activated the filter for scrolling less until I reach the card I'd like to transmute, but then cant use it, thats weird. Same goes for "in possession". And just for the purpose of testing: While trying to transmute a standard card, I already own as premium, with the filters enabled, didnt show the option either. Weird.
Am I missing something why this is useful or is it just a strange bug?
Greetings