The birds just joined the Mile High Club! They were getting into position in the air as they took off. Kudos to them. Many Humans meanwhile are deprived from this due to COVID-19.
edit: I thought YouTube was the only place to be prone to click-bait
I had a similar issue recently with one of the latest BI updates. My overlays were missing from exports. I ended up installing the latest "highly-stable update" (5.2.7.12) and the problem went away. From now on I will only install these highly-stable updates.