drre

never did mead but from what i know issues might be high osmotic stress and low nutrients. I’d dilute a sample to about 16 brix, not higher, maybe lower, add nutrients and yeast and try to restart the fermentation. if you really want to get that high an abv add the undiluted stuff in batches after a couple of days. this way the osmotic stress is at a minimum.

you probably know more than me, but i’d suspect contamination in the cold side, thus

• deep clean everyth ing and make new starsan solution (or something similar)
• check speed of cooling after boiling. final temp should be ok, since it’s apparently cold enough to not kill t he yeast.
• check ph of wort (somwhere i’ve heard that people adjust ph using lactic acid or citric acid, but i’ve never done that in brewing beer.)

good luck!

hmm, how old is the yeast? could be that start of fermentation is slow so that that co2 production is low so that aerobes have longer time to play