As in title, using my "Wings of Hope" with custom pattern, I realised after a while that they are called "Elytra" now. Thought it is a glitch, so I decided to name them, but now they have no pattern (even though pattern list is visible in GUI).

Screenshots as an example (before naming it had orange-yellowy pattern):

I'm using 1.5.4 version, although didn't see any bugfixes on that part in 1.5.5, so I'm assuming it wouldn't change the issue.

Thanks for reporting this!
Looks like it was partially fixed in 1.5.5, but it would still lose its name if you crafted it with a banner.
There's a new version out, 1.5.6, which should fix this fully! :)