LOOKUPVALUE not returning all values

Hi All 

My model: 



I'm trying to find and store the name of the manager (corresponding to manager_id in employment table) in the employment table. I have added a column bossName. 

I've tried both: 

bossName = LOOKUPVALUE('public employee'[FullName],'public employee'[id],'public employment'[manager_id])

and 

bossName = CALCULATE(
	VALUES ( 'public employee'[FullName]),
	FILTER (
		 'public employee',
		 'public employee'[id] = 'public employment'[manager_id]
	)
)

but it works partially: only for two of manager_ids, it gets and populates results and for the rest it's empty/null. 

I've checked and there's corresponding rows for dozens of manager_ids. 

Something to do with relationship or am i missign something in the formula?

Thanks!