I have not heard of your magnitude of problem before.
A few ideas:
Assume the block wall is an 8" wall. If the wall is not grout
filled, perhaps you can insulate the interior of the block cells
with expansive foam
What is your climate? Cold and humidity hitting a hot roof?
Perhaps adding a power vent or several in the area of the problem
to reduce the heat and humidity would help.
You might also consider sealing the "blue stuff" (I don't
recognize the description) with a shellac type sealer to reduce
the damage to the material.
I hope someone has a more direct experience.
Your construction should be listed or detailed as a party wall or
area separation firewall.
Keep the whole world singing . . . .
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