I was unable to reproduce the situation and also the problem I was seeing.
Originally, while I was in the Manticore TF, I was being stunned by the Energy Paragon protectors. I would immediately click on my practiced brawler power to get out of the stun but notice I was being hit as if my toggles were off even while/ a little bit after running away (like a brave hero 🙂 ). I ran in to a similar case again (that same night) in a couple Freakshow radio missions. Each time is was the same scenario, get stunned pop practice brawler, get hit for the next several seconds as if my toggles were still being suppressed.
I noticed it the the Numina TF but as stated earlier that was likely due to the Quartz buff negating SR.
I tried recreating this in the RWZ with Rikti Mezzer and found that the suppressed powers DO come back immediately after freeing myself from sleep and holds. I am trying to see if I can re-create what I was seeing with the Freakshow by doing Freakshow radio missions. So far their stuns last so short a span as to wear off after one of their attacks I can't confirm it. I will up mission to +3 or +4 to try and verify whether I still see this issue, hopefully I can last long enough to get enough data to confirm or debunk this and post what I find.