Slow Then Stuck Sugar Wash

[Hebden]

Can anyone help here, sugar wash started slow and then seems to have stopped at SG 1.012 after 9 days at 85-86f

200L Wash
37.5kg sugar
220g EC1118 (previous working attempt had 500g pitched direct to wash)
B12 x 4 (previous working attempt had 4.5)
B-Complex x 4 (previous working attempt had 4.5)
4 x tbsp DAP (previous working attempt had 4.6)
0.75tsp Epsom Salt

Opening SG 1.070 & 9 day SG 1.012 which looks to have stopped.
Opening pH 5.4 & day 9 pH is 3.5 (this amount of CaCO3 has always kept this wash above 4.5 pH

With only minor adjustments to my wash from a previous working wash, I rehydrated yeast to Lalvin guidelines and pitched at 85f as should be done instructed also.

Lowered pH to 5.4 before adding 400g CaCO3 and then pitching rehydrated yeast to within tolerences given.

This is similar to my previous run which went perfect in 5 days and I know this CaCO3 volume works, I have used it before. Although last time I simply pitched "more" ie 500g yeast directly into the wash, this time the yeasties never seemed to bubble with the usual vigour.
I had thought this was because my pitch rate was halved (again to EC1118 top end guidelines).

Is there anything I can do to save it?

I did do one thing differently and that was to add CaCO3 right after lowering pH and before pitching. Whereas previously, I had added my CaCO3 to my nutrients and sugar and mix all together, therefore "maybe" the CaCO3 smothered the base of the fermenter?