The first time it happened I just thought it was a one-off thing, but now it's happened three times. I go to translate a new rune that I have (that shows as "?" as it should), but when I craft a glyph using that runestone... I get the glyph, but the runestone doesn't translate. For reference, the two runestones I've had this happen with are Lire and Jaedi.
Anyone else encounter this, or got a quick fix for it?