Find keys with no corresponding empty rows

[Torbjorn_Hedberg]

Hi! 

I want find all keys where none of the corresponding values are empty. So in the example below I want "Name two" and "Name three" as a result. Shouldn't be hard but I just can't come up with a way!?  

Key	Value
Name one	123
Name one	345
Name one	456
Name one
Name one	345
Name two	345
Name two	435
Name two	576
Name two	678
Name two	898
Name three	345
Name three	345
Name three	456
Name three	324
Name four
Name four	234
Name four
Name four
Name four	876
Wanted result (no empty cells in row B)
Name two
Name three

[#2 · Accepted solution]

@Torbjorn_Hedberg 

If you have Microsoft 365 or Office 2021:

=UNIQUE(FILTER(A2:A20,COUNTIFS(A2:A20,A2:A20,B2:B20,"")=0))

[#3]

Amazing. Thanks so much!