Size of wrong array. Zeroes out second half of gSequenceChannels[0], all of gSequenceChannels[1..31], and part of gSequenceLayers[0]. However, this is only called at startup, so it's harmless.
This should set the last bank (i.e. the first in the JSON) as default, not the missing one. This code path never gets taken, though – all sequence loading is synchronous.