WowAce

In classic Decursive doesn't work with the Felhunter (who can dispel magic friendlies). No magic debuffs show up in the list etc

Probably related to the fact Imp does the dispels in Retail?

I had this same issue.  You can go to the provided menu for adding spells, and use Devour Magic's spell ID (the name causes a bug) to add it to your list of spells.  Make sure the "magic" box is checked as well as the "pet" one.  You can find the spell ID by looking up the spell on classic wowhead: https://classic.wowhead.com/spell=19505/devour-magic.  So for this example, rank 1 devour magic has a spell ID of 19505.  Let me know if this helps!

It should have been working. Unfortunately there is no PTR like in retail so I cannot easily test this.

type /dcr diag and past the content of the window here

/dcr diag returns "unknown argument".

What elilauff posted above did fix the issue however.

Sorry it's in one word /dcrdiag

closing due to no answer