Unreal: Cannot create render instance

Creating render instances seems very sensitive. Sometimes I can only create render instance for one shot and when I try to add a second shot I get this

“Warning: Skipping coolestShotEver. It isn't a sub-sequence of the master sequence.”
(even though it is clearly a part of the master sequence)

If I restart Unreal I can add another shot. But only on at a time then I have to restart Unreal again.

Also sometimes I could not add any render instances anymore and had to re-create my master sequence in order to add more renders.

All of this is probably very hard to re-create as it is very random when things work and do not work. But maybe there are ways to simplify things to make it less sensitive? (I made another ticket to be less dependent on master sequence)