Two thing I can contribute.
1/ I use a single (only one I can get here) systemic fungicide without issue but this year I had tried it at bud break on several species to combat perpetual problems from the outset eg. powdery mildew on white oaks, I was apprehensive about using it on such young soft leafs. I found it deformed the growth of the maturing leaves on several, I looked into it and it is normal in some species, depends on the match of which fungicide on what plant.
2/ I repotted this last spring from a very sandy well draining soil (watered every two weeks due to waxy leaves) because it had basically stopped growth, to an all inorganic soil lava, DE & river stone, watered daily now and I have never seen it grow so well! Getting rid of the organics was the right choice, but watering less may have helped too, though the leaves do not look to be the same waxy ones a benjamina has.
For what it's worth my benjamina loves the sun but does okay with a good defused light, it just grows slower. It grows aerial roots in our humid summers and loses them in the dry central heat in winter. When it was in the sandy mix for 20 years it still only needed watering once a week to 10 days in the dry of winter. Also I did not use this fungicide on the benjamina I have never used anything other than water and fertilizer but I see deformed leaves from time to time, just a couple, no big deal but I don't know why.
Good luck but it looks like you might have found the problem.
... They just occupy space.. empty. 
