Incorrect extents passed to BinMD from sliceviewer when first change slicepoint by small increment

[RichardWaiteSTFC]

Describe the bug

Incorrect extents passed to BinMD from sliceviewer when first change slicepoint by small increment - it looks like BinMD is not called?

To Reproduce

# (1) Create workspace
ws_3D = CreateMDWorkspace(Dimensions='3', Extents='-1,1,-1,1,-1,1',
                          Names='H,K,L', Units='r.l.u.,r.l.u.,r.l.u.',
                          Frames='HKL,HKL,HKL', SplitInto='2', SplitThreshold='50')  # enabled!
                          
# (2) open sliceviewer

# (3) use the spinbox to set slicepoint (along L) to 0.01

# (4) run this code to print the integration limits

ws_mdhisto = mtd[ws_3D.name() + "_svrebinned"]
alg = ws_mdhisto.getHistory().lastAlgorithm()
limits = [float(lim) for lim in alg.getPropertyValue("OutputExtents").split(",")[-2:]]
print("slicepoint = ", np.mean(limits))
print("integration limits = ", limits)

# slicepoint =  0.0
# integration limits =  [-0.05, 0.05]

Expected behavior

Should print

# slicepoint =  0.01
# integration limits =  [-0.04, 0.06]

Platform/Version (please complete the following information):

• OS: IDAaaS
• Mantid Version 6.9.20240514.1920 (manual testing) - but present in v6.9

Additional context
Found during core testing #37325