Pantheon vessel capture not working

When trying to capture Otesha the Giantslayer in a tier 7 iceberg map for soul of lunarins, it just consumes the vessel - it does not get filled and returned. I have tried 3 times now. It worked fine for Fragment of Winter in between.

Same issue here. T16 Iceberg, cannot capture Otesha.

I captured every single other one no problem, but Otesha does not work. Vessel just disappears and does not go into inventory.