Z height issue - CAM/Post Processor/Controller/Mill?

[Dangle_kt]

New boy alert! Got a weird issue I wanted to run past folk please.

Just ran a prototype part, first op (adaptive clearing went well), 2nd op was a 0.1mm face op... which actually came in an hammered a approx 3mm depth of cut, scrapping the part and nearly giving me a heart attack.

I think the G code is ok which means fusion 360 and the post processor was fine, but as I am rubbish at reading g code I wanted to get advice from more experienced heads so I can rule out Fusion and the post processor please - so can you check the code below and see if you can see any reason it messed up?

z0 was stock top, which was 0.1 from model top. I'm running a 10mm endmill into alu. This is the exerpt of the face op

(FACE2)
N2559 G0 X86.5 Y3.675
N2560 Z15
N2561 Z5
N2562 G1 Z0.9 F400
N2563 G18 G3 X85.5 Z-0.1 I-1
N2564 G1 X80
N2565 X0
N2566 G3 X-1 Z0.9 K1
N2567 G0 Z5
N2568 G1 X86.5 Y12.255 F4000
N2569 Z0.9 F400
N2570 G3 X85.5 Z-0.1 I-1
N2571 G1 X80
N2572 X0
N2573 G3 X-1 Z0.9 K1
N2574 G0 Z5
N2575 G1 X86.5 Y20.835 F4000
N2576 Z0.9 F400
N2577 G3 X85.5 Z-0.1 I-1
N2578 G1 X80
N2579 X0
N2580 G3 X-1 Z0.9 K1
N2581 G0 Z5
N2582 G1 X86.5 Y29.415 F4000
N2583 Z0.9 F400
N2584 G3 X85.5 Z-0.1 I-1
N2585 G1 X80
N2586 X0
N2587 G3 X-1 Z0.9 K1
N2588 G0 Z5
N2589 G1 X86.5 Y37.995 F4000
N2590 Z0.9 F400
N2591 G3 X85.5 Z-0.1 I-1
N2592 G1 X80
N2593 X0
N2594 G3 X-1 Z0.9 K1
N2595 G0 Z5
N2596 G1 X86.5 Y46.575 F4000
N2597 Z0.9 F400
N2598 G3 X85.5 Z-0.1 I-1
N2599 G1 X80
N2600 X0
N2601 G3 X-1 Z0.9 K1
N2602 G0 Z5
N2603 G1 X86.5 Y55.155 F4000
N2604 Z0.9 F400
N2605 G3 X85.5 Z-0.1 I-1
N2606 G1 X80
N2607 X0
N2608 G3 X-1 Z0.9 K1
N2609 G0 Z15
N2610 G17

I'll add a photo of the physical part.

Would welcome your diagnosis as my suspicion is currently on the controller/machine.

Thanks folks!