Ok I found your error:

[     93625] Error running call reference function for resource esx_ambulancejob: citizen:/scripting/lua/scheduler.lua:403: client/job.lua:522: attempt to index a nil value (global 'PlayerData')
[     93625] stack traceback:
[     93640] 	client/job.lua:522: in function 'OpenCloakroomMenu'
[     93640] 	client/job.lua:22: in upvalue 'ref'
[     93640] 	citizen:/scripting/lua/scheduler.lua:389: in function <citizen:/scripting/lua/scheduler.lua:388>
[     93640] 	[C]: in function 'xpcall'
[     93656] 	citizen:/scripting/lua/scheduler.lua:388: in function <citizen:/scripting/lua/scheduler.lua:387>
[     93656] stack traceback:
[     93656] 	[C]: in function 'error'
[     93672] 	citizen:/scripting/lua/scheduler.lua:403: in function <citizen:/scripting/lua/scheduler.lua:372>

It means it can’t access to PlayerData and by looking above I see it’s a ESX attribute, so your condition need to be:

if ESX.PlayerData.job.grade_name == 'boss' then
		table.insert(elements, {label = 'Sheriff wear', value = 'freemode_ped', maleModel = 's_m_y_sheriff_01', femaleModel = 's_f_y_sheriff_01'})
	end