After grinding vMA for a couple weeks, I've noticed some recurring issues pop up consistently from run to run. The arena is meant to be difficult, so I've made sure to only note things that seem like technical issues or poor design issues.

STAGE SPECIFIC ISSUES
-Stage 1 - Clanfear leap attack animation looks awkward when initiated from long range
-Stage 2 - Flipping switches sheathes weapons
-Stage 4 - Clockwork sentries are immune before their shields come up
-Stage 5 - Ice islands don't allow smooth transition from water, causing player to get stuck
-Stage 7 - Poison plants sometimes ignore player proximity (usually between rounds), preventing the player from strategically baiting the explosion
-Stage 9 - Voriak Solkyn's necrotic blast interrupts/ignores player roll dodge (upper level crystal phase, specifically)

COMBAT CUE ISSUES
-Attack effects not representative of their effective areas (or latency favors server over client);
---Clanfear leap attack (stage 1)
---Lamia Queen scream aoe (stage 3)
---Matriarch Runa's ground trail (stage 5)
---Argonian Minder aoe after teleport (stage 7)
---Infernal destroyer flame trail/path AOE (stage 8)
---Most trail/path AOEs that radiate out from enemy (any stage)

-Attacks without combat cues;
---Most trail/path AOEs that radiate out (excluding infernal destroyer)
---Crematorial guard flame breath

GENERAL ISSUES
-Bash fails to interrupt enemies despite being close enough (archers, dremora kyngalds, Voriak solkyn, etc.)
-Synergies are unresponsive
-Player AOEs expire/disappear before their duration is up (true outside of arena as well)
-Player skills activate upon resurrection if they were used right before dying

Nitpicks
-Larger mobs like the Frost Atronach (stage 5) and the Infernal Destroyer (stage 8) don't represent their large melee range very well. It might be an animation issue.
-Synergies' visual effects on the player could be more intense
-Dremora Narkynaz (stage 9) take very long to summon a Bone Colossus. Could probably be more punishing
-Spectral explosion (stage 9) being available makes synergies unusable
-Stage 1 feels too bland/simplistic