Lets say I have dev1 development branch.
I have finished the work and sent it to review.
But I need to continue development of another feature while first one is on review.
So I create dev2 brunch and merge dev1 to dev2.
dev1 passed a review so I merge it to master using squash.
Now when I do a reverse merge from master to dev2 I need to perform manual merge.

What is wrong with my workflow?

Update:
Squash is mandatory due to project policies.