Volley does not show up in either single target or AoE in the default action lists for 9.0.5-1.0.4. Not sure if that is intentional but I couldn't get it to trigger and I find it hard to believe there are no scenarios you would want it.

build: v9.0.5-1.0.4
level: 60 (60)
class: HUNTER
spec: marksmanship

talents: double_tap
explosive_shot
master_marksman
natural_mending
posthaste
streamline
volley

pvptalents: none

covenant: kyrian

conduits: enfeebled_mark = 5
markmans_advantage = 5
powerful_precision = 5
resilience_of_the_hunter = 5

soulbinds: [pelagos]
cleansed_vestments = 1
combat_meditation = 1
focusing_mantra = 1
let_go_of_the_past = 1

sets: none

gear: absonant_constructs_handguards = 1
antisepticsoaked_dressing = 1
boneshatter_pauldrons = 1
dealer_xyexas_cape = 1
executors_prideful_girdle = 1
fleshfused_circle = 1
gormhusk_kilt = 1
guild_tabard = 1
instructors_divine_bell = 1
overcharged_anima_battery = 1
rattling_deadeye_hood = 1
ritualists_treasured_ring = 1
spatial_rift_striders = 1
tortured_assistants_bindings = 1
trailspinner_pendant = 1
triumphant_combatants_chainmail = 1
xy_cartel_crossbow = 1

legendaries: serpentstalkers_trickery = 1

itemIDs: 172327, 178707, 178738, 178767, 178794, 178843, 178869, 179345, 179348, 179349, 180105, 180116, 181416, 183037, 184842, 44694, 5976

settings: aoe = 3
buffPadding = 0
custom1Name = Custom 1
custom2Name = Custom 2
cycle = false
cycle_min = 6
damage = true
damageDots = false
damageExpiration = 6
damagePets = false
damageRange = 0
debuffPadding = 0
enabled = true
enhancedRecheck = false
gcdSync = true
maxRefresh = 10
maxTime = 33
nameplateRange = 8
nameplates = false
package = Marksmanship
petbased = false
potion = spectral_agility
potionsReset = 20180919.1
throttleRefresh = false
throttleTime = false
prevent_hardcasts = false
trueshot_vop_overlap = false

toggles: cooldowns = false
custom1 = false
custom2 = false
defensives = true
essences = true
interrupts = false
mode = automatic
potions = false

Please follow the ticket instructions. If you have an issue with recommendations, you need to post a snapshot (see instructions) when it's happening.

Volley does appear in the priority for Marksmanship.

My apologise, first time submitting any kind of bug report. Below is the snapshot just sitting in town where Volley is normally the 4th recommended use, but since 1.0.4 never comes up for my setup.

https://pastebin.com/BDAxYBve

35.  volley ( st - 12 )
The action (volley) is usable at (3.55 + 1.33).
 - the action is ready before the current recommendation (at +1.33 vs. +60.00).
List ( st ) called from ( Marksmanship:default:9 ) would PASS at 1.33.
active_enemies[1.00] < 3
 - this entry's criteria FAILS: ( buff.resonating_arrow.up[false] | ! covenant.kyrian[true] | talent.lethal_shots.enabled[false] ) & ( buff.precise_shots.down[false] | ! talent.chimaera_shot.enabled[false] | active_enemies[1.00] < 2 )
12.335668298649 - true
There are 1 recheck events.
Rechecking stopped at step #1.  The recheck ( 13.66 ) isn't ready within a reasonable time frame ( 10s ).
Time spent on this action:  0.40ms

The conditions for Volley have changed in single-target (same with your sims).

It requires one of:

• Resonating Arrow is up
• You're not Kyrian
• Lethal Shots is talented

And one of:

• Precise Shots is down
• Chimaera Shot is not talented
• There is only 1 enemy

You would meet the latter criteria but not the former.