LT8640S - LTspice simulation of synchronous clocking - example jig does not seem to support this modelling

I understand from the datasheet that the switching clock can be controlled by applying a clock to the Mode (sync) input. I cannot confirm this with simulation in LTspice. The internal clock does not track the externally applied clock - nor does the clkout. Am I doing something wrong?

  

Version 4
SHEET 1 1848 740
WIRE 64 -80 -32 -80
WIRE 208 -80 64 -80
WIRE 432 -80 208 -80
WIRE -32 -64 -32 -80
WIRE 208 -64 208 -80
WIRE 64 0 64 -80
WIRE 112 0 64 0
WIRE 432 0 432 -80
WIRE 432 0 400 0
WIRE 64 16 64 0
WIRE 432 16 432 0
WIRE -32 32 -32 16
WIRE 64 96 64 80
WIRE 112 96 64 96
WIRE 432 96 432 80
WIRE 432 96 400 96
WIRE 64 112 64 96
WIRE 432 112 432 96
WIRE 32 192 0 192
WIRE 112 192 96 192
WIRE 544 192 400 192
WIRE -96 288 -144 288
WIRE 112 288 -96 288
WIRE -144 352 -144 288
WIRE -16 384 -48 384
WIRE 112 384 64 384
WIRE 432 384 400 384
WIRE 544 384 544 192
WIRE 544 384 512 384
WIRE 656 384 544 384
WIRE 752 384 656 384
WIRE 848 384 752 384
WIRE 544 400 544 384
WIRE 656 400 656 384
WIRE 752 400 752 384
WIRE 848 400 848 384
WIRE -144 464 -144 432
WIRE 32 480 0 480
WIRE 112 480 96 480
WIRE 544 480 400 480
WIRE 656 480 656 464
WIRE 656 480 544 480
WIRE 544 496 544 480
WIRE 752 496 752 464
WIRE 848 496 848 480
WIRE 304 560 304 544
WIRE 208 592 208 544
WIRE 544 592 544 576
WIRE 208 608 208 592
FLAG 304 560 0
FLAG -48 384 0
FLAG -32 32 0
FLAG 0 192 0
FLAG 752 496 0
FLAG 544 592 0
FLAG 848 496 0
FLAG 848 384 OUT
FLAG -32 -80 IN
FLAG 64 112 0
FLAG 432 112 0
FLAG 0 480 0
FLAG -144 464 0
FLAG 208 592 clko
FLAG -96 288 sync
SYMBOL res 80 368 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R1
SYMATTR Value 40k
SYMBOL voltage -32 -80 R0
SYMATTR InstName V1
SYMATTR Value 24
SYMBOL cap 96 208 M270
WINDOW 0 32 32 VTop 2
WINDOW 3 0 32 VBottom 2
SYMATTR InstName C2
SYMATTR Value 1µ
SYMBOL ind 416 400 R270
WINDOW 0 32 56 VTop 2
WINDOW 3 5 56 VBottom 2
SYMATTR InstName L1
SYMATTR Value 3.3µ
SYMATTR SpiceLine Rser=10m
SYMBOL cap 736 400 R0
SYMATTR InstName C4
SYMATTR Value 47µ
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0.002 Lser=0 mfg="TDK" pn="C4532X5ROJ47@M" type="X5R"
SYMBOL res 528 384 R0
SYMATTR InstName R2
SYMATTR Value 1Meg
SYMBOL res 528 480 R0
SYMATTR InstName R3
SYMATTR Value 243K
SYMBOL cap 640 400 R0
SYMATTR InstName C5
SYMATTR Value 4.7p
SYMBOL res 832 384 R0
SYMATTR InstName Rload
SYMATTR Value 1
SYMBOL cap 48 16 R0
SYMATTR InstName C6
SYMATTR Value 1µ
SYMBOL cap 416 16 R0
SYMATTR InstName C7
SYMATTR Value 1µ
SYMBOL cap 96 496 M270
WINDOW 0 32 32 VTop 2
WINDOW 3 0 32 VBottom 2
SYMATTR InstName C1
SYMATTR Value 1n
SYMBOL PowerProducts\\LT8640S 256 240 R0
SYMATTR InstName U2
SYMBOL voltage -144 336 R0
WINDOW 3 -110 234 Left 2
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR Value PULSE(0 3 0 1n 1n {1/(2*900k)} {1/(900k)})
SYMATTR InstName V2
TEXT 704 576 Left 2 !.tran 750u startup
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