I've got the 11.2.2 update, iPhone 6 Plus. Thousands of songs over decades. Standard "UNSYNCEDLYRICS" tag in the metadata inserted through various programs over the years ranging from Winamp to Mp3tag to automatic stuff like Lyrics Finder.
Up until iOS 11, all lyrics displayed all the time, flawlessly. Now, after the cumbersome 6-step process, only a minority of them show lyrics. The tags are all the same, so perhaps my iPhone is only picking them up if the UNSYNCEDLYRICS tag is in a certain numerical spot among the various metadata, who knows?
Clearly there is variance from model to model of Apple device, and equally clearly, Apple needs to roll back to an earlier version that works on everything. Apple, once upon a time, was known for products that "just worked." Their stuff is a closed-source walled garden to prevent this precise kind of ish from happening. Shame on them.