Shield lob not working - You're doing it wrong

Okay, just for fun! I kept my (would be) original question below

For some weird reason my shield was unequiped (?) and I did not notice (??)
What I did notice was: Shield lob was not working. after researching everything (except my equipment) I came here to see if anyone had a hint to what was wrong.

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Weird thing happened today. My shield lob and shield bash stopped working.
Lv 30 GLA on my LV30 class quest. Says "Cannot use it yet"
Q: Am I missing something?
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A: your shield! nimrod

I had this happen to me once in an old 24 person raid from 2.0 era. Like you I found myself without a shield, which was a real problem cause you needed one for tank stance back then. The answer I found was that I had upgraded my old shield to a higher ilevel one but never updated the gear set. Since tanks don't get instant queues for 24 person raids I did a bit of mining while I waited. When it popped I switched back and quickly accepted. Since a job only needs a Main Hand to work the game gave me no warnings other than the standard not all gear found massage, which I failed to notice in my haste to click the ready button.

Since then I've always made a note of updating my gear set the very moment I get anything new so it doesn't happen again.