Although I haven't had any issues with "ScriptElt" as of yet - I do experience a no show of the playable within the ads dashboard of facebook sometimes - but when live, it shows. I sent them an email about the issue yesterday. I was informed that they are aware of some issues on their playables platform. Seems related to the recent outage. From my experience, they are usually rather quick to respond to these types of issues. Especially since playable ads are extremely effective and a huge portion of spend in marketing terms.
Are you guys using the Facebook Object? - I don't use it and have zero "ScriptElt" errors. I'm curious if that has something to do with it. Try removing it, you don't need it for a FB playable ad. I use the Browser plugin - as I have posted prior with an "execute javascript" action for the exit API. Which works for other ad networks as well.
A few places to test out your playable to see if it will work:
Iron source :
https://demos.ironsrc.com/test-tool/?adUnitLoader=dapi&mode=testing
Applovin:
https://p.applov.in/playablePreview?create=1
These ad networks require the same data URI inlined single html file approach that facebook does - so it's a great way to test them. You will however have to adjust the exit API accordingly to test.