Judging by both the GP's not having been aware of it, and the process described in a sibling comment [1], I suspect the feature has a discoverability problem.
(Does the same feature exist on mobile? How are file attachments represented on mobile?)
(Does the same feature exist on mobile? How are file attachments represented on mobile?)
It works perfectly fine, with no missing features. I use it to store private keys and recovery codes, mainly.