Im also havign this issue, just flipped from invoker to bombardment using Trinity 2.14.31 and Adventurer 1.3.4.14.
Seam to be reinstalling or updating trinity or adventurer every few days over last 2 weeks
>EDIT<
Havent changed anything and seams to be working 2 rifts later for no reason, that said noticed it pops iron skin before it pops bombardment while ring is in lighting before cycling to physical. Unsure if its a snapshot effect but if it isnt like the ring doesnt seam to be its wasting a few seconds per CoE cycle by casting this just before instead of slightly after?
Also guessing built in combat settings overriding any additional settings for shield glare as its seams to use it on cd on elites a few seconds before CoE cycle and thus missing the 20% increased dmg with the full combo.
It takes a few seconds for the first barrel from bombardment to hit, CoE is dynamic so this is the most efficient.