Looping will not render

I am trying to get a video clip of 2 photos that merge together to loop. On the edit & render pages the looping works, but after rendering, the finished video just runs & stops without looping. Has anyone else had this problem and do you have a solution?
I’m using Davinci Resolve 17.1.1. I also have the last version 16 and it’s the same with that.
I’m using Davinci Resolve 17.1.1. I also have the last version 16 and it’s the same with that.