Re gif from snapshot bug, I don’t know I would need to look when I have some time as I only do 5 second recordings. It is possible that the camera takes longer to reply to some requests then others and this means the pictures come back in a different order. You did state (do i remember correct?) once your camera was not taking a consistent time to reply with a snapshot and that may be the cause.
Regarding OOME we need to solve this one first as you can not trust a system that this has occurred on. Forget other issues until you no longer run out of heap space…
The only time I has seen this is when using the image channel, do not use the image channel.
How did you setup the PI3? Did you use openhabian or do it yourself? What is your heap size?
See this post on how to check and increase the heap size.