Mob with custom follow range doesn't seem to work

In Minecraft Java Edition, I have made a custom mob (which is ridden by another invisible mob) using this generator: https://www.gamergeeks.nz/apps/minecraft/mob-generator , and in the Attributes tab I set the "follow range" of both to 50 blocks. In theory, this should mean that they detect and attack any player within a 50 block radius, if I'm not mistaken.

In practice, this doesn't happen. The mob doesn't attack until I'm within 10-11 blocks of it. This is the (long) command I used to summon it:

/summon minecraft:skeleton 2877 4 -235 {CustomName:'[{"text":"Suppressor unit","color":"gold"}]',CustomNameVisible:0b,Health:40,PersistenceRequired:1b,Silent:1b,HandItems:[{id:crossbow,Count:1}],ArmorItems:[{id:iron_boots,Count:1},{id:iron_leggings,Count:1},{id:netherite_chestplate,Count:1},{id:turtle_helmet,Count:1}],Attributes:[{Name:"generic.movement_speed",Base:0.09f},{Name:"generic.max_health",Base:40F},{Name:"generic.follow_range",Base:50F}],HandDropChances:[0F],ArmorDropChances:[0F,0F,0F,0F],Passengers:[{id:guardian,Health:20,PersistenceRequired:1b,ActiveEffects:[{Id:14,Amplifier:0,Duration:99999999}],Attributes:[{Name:"generic.armor"},{Name:"generic.max_health",Base:25F},{Name:"generic.attack_damage",Base:15f},{Name:"generic.follow_range",Base:50f}]}]}

The parts relating to the follow range are in bold. So, why this discrepancy? If it's an issue of the command just not working as it should, is there any possible workaround?

There's a bug in the game where follow range only changes the distance at which the mob will follow you once seen. Follow range does not apply to the generic seeing distance, which is 16 for most mobs and 40 for zombies and I think pillagers, so setting a higher follow range will not enable mobs to see you and attack you from farther away.