I'm currently having the same issue moving armor from Lae'zel to anyone besides Gale, also I can't seem to equip any medium armor on my druid.
EDIT: so it seems that Lae'zel's armor and the chain shirt +1 are bugged. They cannot be equipped by my PC I thought it might be a druid rule about armor like in 3.5 D&D but that rule doesn't exist in 5e and I can equip shadowhearts medium armor. So in conclusion... Bugged...
