Okay because you have tried with no mods in your mod list, try my config for Lua's Spawn Rework I'll put it as a spoiler for you in a few parts as only 10,000 words are allowed. Also only have this mod in your list, hopefully it should spawn in Sniper Scavs.
{
"PLEASE READ [Config_ReadMe.txt] BEFORE EDIT!": "",
"script_file": "Lua-Default.js",
"spawns":{
"max_alive_bots": 14,
"local_bots_count": 60,
"ai_max_warns_before_kill": 1,
"scav_groups_together": false,
"pmc_usec_chance": 50,
"customs":{
"map_rules": "AvoidAllPmc",
"show_generated_bots":"secret",
"max_spawn_time": 700,
"max_spawn_time_limit_warning":false,
"max_bot_per_zone": 12,
"allow_other_bot_spawn_with_boss":false,
"has_boss":true,
"bosses_spawn_location_type":"evenly",
"max_boss":1,
"boss_spawn_trying_loop":1,
"allow_same_boss_spawn":false,
"bosses_also_use_scavs_spawn_locations":false,
"bosses_also_use_raiders_spawn_locations":true,
"cultists_spawn_count_for_max_boss": false,
"cultists_spawn_at_own_locations": true,
"boss_settings":[
{
"name":"bossBully",
"chance":36,
"difficulty":"normal, hard",
"escort_type":"followerBully",
"escort_difficulty":"normal, hard",
"escort_amount_min":2,
"escort_amount_max":4,
"wave_total":1,
"wave_spawn_time_for_each_min":2,
"wave_spawn_time_for_each_max":2,
"wave_spawn_all_same_location":false,
"spawn_locations":{
"ZoneScavBase":1,
"ZoneGasStation":1,
"ZoneDormitory":1
},
"trigger_id":"",
"trigger_name":"",
"supports":null
},
{
"name":"sectantPriest",
"chance":20,
"difficulty":"normal, hard",
"escort_type":"sectantWarrior",
"escort_difficulty":"normal, hard",
"escort_amount_min":1,
"escort_amount_max":3,
"wave_total":1,
"wave_spawn_time_for_each_min":2,
"wave_spawn_time_for_each_max":2,
"wave_spawn_all_same_location":false,
"spawn_locations":{
"ZoneDormitory":1
},
"trigger_id":"",
"trigger_name":"",
"supports":null
},
{
"name":"bossBully, bossGluhar, bossKilla, bossKojaniy, bossSanitar, bossTagilla",
"chance":20,
"difficulty":"normal, hard",
"wave_total":1,
"wave_spawn_time_for_each_min":2,
"wave_spawn_time_for_each_max":2,
"wave_spawn_all_same_location":false,
"spawn_locations":{
"ZoneScavBase":1,
"ZoneGasStation":1,
"ZoneDormitory":1
},
"trigger_id":"",
"trigger_name":"",
"supports":[
{
"BossEscortType":"pmcBot, assault",
"BossEscortDifficult":[
"normal, hard"
],
"BossEscortAmount_min":1,
"BossEscortAmount_max":2
},
{
"BossEscortType":"sectantPriest, followerBully, followerKojaniy, followerSanitar, followerGluharSnipe, followerGluharAssault, followerGluharScout, followerGluharSecurity",
"BossEscortDifficult":[
"normal, hard"
],
"BossEscortAmount_min":1,
"BossEscortAmount_max":2
}
]
}
],
"wave_settings":{
"scav_waves":{
"wave_total":6,
"slot_min":1,
"slot_max":3,
"insta_spawn_waves":2,
"spawn_time_delay_after_insta_wave": 0,
"spawn_time_delay_for_each_min": 90,
"spawn_time_delay_for_each_max": 120,
"spawn_time_delay_accumulate_for_each_zone": false,
"spawn_location_type": "random",
"difficulty":{
"easy":0,
"normal":3,
"hard":3,
"impossible":0
},
"spawn_locations":{
"ZoneBrige":1,
"ZoneCrossRoad":1,
"ZoneOldAZS":1,
"ZoneBlockPost":1,
"ZoneDormitory":1,
"ZoneGasStation":1,
"ZoneFactoryCenter":1,
"ZoneFactorySide":1,
"ZoneWade":1,
"ZoneScavBase":1,
"ZoneTankSquare":1
}
},
"sniper_waves":{
"wave_total":2,
"slot_min":1,
"slot_max":1,
"insta_spawn_waves":1,
"spawn_time_delay_after_insta_wave": 0,
"spawn_time_delay_for_each_min": 90,
"spawn_time_delay_for_each_max": 120,
"spawn_time_delay_accumulate_for_each_zone": false,
"spawn_location_type": "evenly",
"difficulty":{
"easy":0,
"normal":1,
"hard":2,
"impossible":0
},
"spawn_locations":{
"ZoneSnipeTower":1,
"ZoneSnipeFactory":1,
"ZoneSnipeBrige":1,
"ZoneBlockPostSniper":1,
"ZoneBlockPostSniper3":1
}
},
"raider_waves":{
"raider_random_role":false,
"raider_random_role_chance":0,
"raider_random_role_list":"followerBully, followerGluharAssault, followerGluharScout, followerGluharSecurity, followerGluharSnipe, followerKojaniy, followerSanitar",
"wave_total":0,
"slot_min":0,
"slot_max":0,
"insta_spawn_waves":0,
"spawn_time_delay_after_insta_wave": 0,
"spawn_time_delay_for_each_min": 0,
"spawn_time_delay_for_each_max": 0,
"spawn_time_delay_accumulate_for_each_zone": false,
"spawn_location_type": "random",
"difficulty":{
"easy":0,
"normal":1,
"hard":3,
"impossible":0
},
"spawn_locations":{
"ZoneDormitory":2,
"ZoneGasStation":2,
"ZoneWade":1,
"ZoneScavBase":1,
"ZoneCrossRoad":1
}
},
"pmc_waves":{
"cursedAssault_chance":33,
"wave_total":5,
"slot_min":1,
"slot_max":5,
"insta_spawn_waves":2,
"spawn_scav_raider_location_chance": 10,
"spawn_time_delay_after_insta_wave": 180,
"spawn_time_delay_for_each_min": 300,
"spawn_time_delay_for_each_max": 480,
"spawn_time_delay_accumulate_for_each_zone": false,
"spawn_location_type": "random",
"difficulty":{
"easy":0,
"normal":0,
"hard":2,
"impossible":2
},
"spawn_locations":{
"ZoneDormitory":2,
"ZoneGasStation":2,
"ZoneWade":1,
"ZoneScavBase":2,
"ZoneCrossRoad":1,
"ZoneCustoms":1
}
}
}
},