As of 03/21/2018 we had identified an issue with runes / glyphs that increase attack speeds (Frenzy). The runes / glyphs were increasing tower attack speed in a way similar to Lightning Towers resulting in no actual gain of attack speed for most users.
We have fixed this issue so that runes / glyphs increase tower attack speed by a flat percentage. This change will be most noticeable to users who have one of a specific tower on the island boosted by the rune / glyph.
There may be some edge cases where the percentage enhancement to tower attack speed increases the tower by such a small amount that no visible change occurs. This is not a bug, but if you have any questions you should reach out to our support team.