Multiple of my friends on Instagram still post daily about the atrocities in Gaza, but haven't posted anything about the atrocities in Aleppo or Kobane. Nor did they post anything when the STG was massacring the Alawites or the Druze last year.
So I find it hard to believe that it's about the sanctions or whatnot.
I personally protested for Sudan, Syria and Venezuela. Of course you might say I am just giving you excuses, but on a personal level I feel different for each one of them when protesting, my expectations also different:
* Sudan - IMO it was funded by UAE, our gov. can sanction them, but they have excuse: "Do you have proof???"
* Syria - Their excuse: "What are you talkin about, we don't cooperate with ex-Al-Qaeda, what can we do there?"
* Venezuela - "Dude, we are doing it, just shut the f... up and watch how awesome we are in conducting these operations"
* Gaza - I think initially we were naive thinking our government will help, but in reality it turned out it was same government, so it resembles more to Venezuela case rather than other cases.