I generated the G-code in Fusion 360. I ran the file and Z axis retracts to zero and the program pauses were indicated without any prompt. If I skip the indicated line the program runs as expected.

It almost seems like waiting for manual tool change. What am I missing?

Code:
%
(SPOILBOARD)
(1ST ATTEMP AT SPOIL BOARD)
(T1  D=6.35 CR=0. - ZMIN=-19. - FLAT END MILL)
N10 G90 G94 G17 G91.1
N15 G21
N20 G53 G0 Z0.  <<<<<<<<<<<executes this line then stops>>>>>
(BORE1)
N25 T1 M6
N30 S5000 M3
N35 G54
N40 G0 X44.18 Y49.702