Well, from the pulls I had on Mythic Paragons, it seems that Skeer does that after releasing your spirit too fast.
It always happened with Rik'kal still alive. If I didn't manage to kill Rik'kal fast enough, and died, the different enemies would take a considerable amount of time before despawning, leading them to enter in combat with me while resurrecting in the raid, and thus leading the encounter to bug on the next attempt, and reset.
To counter this bug, just waiting a few seconds (10-15) before releasing spirit is enough.
From the moment I entered in combat right after coming back to life, I knew I had to throw one pull without any components in order not to waste time and money (components).
About ToT 25N/HM,
If you have the possibility to generate a source of aggro on one of Magaera's heads (Elemental? Mirror Images? - I do so with my Statue as a Monk), you are able to deviate the breaths from that head, making the encounter 20 times easier (as an indicator, the boss could be done in 10 Heroic difficulty with 620 ilvl with that Strategy, over 660+ without, for my class). You only have to focus on one head to survive on, therefore. Also, the damages of Rampage should be the same between 10 and 25 players versions. Just saying, if you're looking for a funny encounter in terms of timing
.
With that Strategy, it's possible to stay infinitely with the Purple head being tanked, in Heroic difficulty, preventing the mana mobs annoyances from appearing (they can't appear while the Purple head is alive).
That aside, well done for your recent achievements