"Working on" since 2012?
I don't use IG, so I wasn't aware of that problem or how long it had been around. That said, the general sentiment stands: one of their teams working on one thing doesn't show that they don't have another team working on something unrelated.
This is likely it, right here. So many people forget that larger companies have different teams working on different things. I bet a lot of their "iOS people" that are working on this project have no clue how the Android app works, and Instagram likely has a separate team working on the compression issues.