Possibly ARENA_* events are fired mid match?
It was vs a rogue mage team.

ArenaEnemyFrame_OnEvent(self, event, unit, ...)
if ( event == "ARENA_OPPONENT_UPDATE" ) then
local unitEvent = ...;

unitEvent includes "seen", "destroyed", "unseen", "cleared", etc.

So we shouldn't reset everything in case of this event, just clear cache with event
ARENA_PREP_OPPONENT_SPECIALIZATIONS

Fixed in #8