Goog ol' Leslie's, does not list anything for ingredients for the NoPhos or the Clarifier, even in their required MSDS reports. So unknown if you had a chem reaction. They do note to not use NoPhos right after the conditioner.
We can't at all trust their numbers, but if your CYA is really now at ~40, you would need a Cl level of 5-7 after the SLAM. Their sheet says you were about 3. So that would tell the tale - an algae bloom.
But all this is speculation, as all we know for sure is that their testing is ALWAYS wrong.
You spent about $112 in chems from them, and it didn't work. So invest less than that in a good test kit, and we can get you back to a really clear pool for far, far less.