Problem with function for count with criteria

Perhaps just make the second formula

{=SUM(('Master log'!K:K="")*('Master log'!L:L<>"")*('Master log'!D:D="HJT"))}

or if you want to count both in one formula

{=SUM(('Master log'!K:K&L:L<>"")*('Master log'!D:D="HJT"))}