Help with zombie villager conversion tick

I'm writing a datapack to kill all villagers except those converted from zombie villagers. I'm making it so that an armorstand summons and gives the converted villager a tag then deletes itself. Everything works fine except the armor stand doesnt summon. Here is the line I'm using that doesnt seem to work:
execute as @e[type=minecraft:zombie_villager,nbt={ConversionTime:20}] at @s run summon minecraft:armor_stand ~ ~ ~ {Tags:["vc_cure_marker"],Invisible:1b,Invulnerable:1b,NoGravity:1b,Marker:1b}
When I freeze the tick at 20 on the zombie conversion time, then run the armor stand summon - it works. But if it naturally ticks down to 20 it seems to skip over this command. Not sure what to do!