Nbt Tags doesn't work?

I tried to activate my function now because it doesn't worked in 18ww01a and got fixed but now the Nbt Tag doesn't work

Example:

/execute at @e[type=bat,name=enderhopper] as @e[type=bat,name=enderhopper] run summon armor_stand ~ ~1 ~ {CustomName:"hopper"}

without the

{Customname:"hopper"}

it does work but if i do it with the Nbt tag

it say's:

"Unable to Summon entity"