Is there such a sentence - this stagnant problem?

"This stagnant problem" is grammatically correct, but it's not a complete sentence. It's a phrase that describes a problem that is not moving forward or progressing.

Here's how you can use it in a complete sentence:

* "This stagnant problem needs to be addressed immediately."

* "We've been stuck with this stagnant problem for months."

* "The company's lack of innovation is a stagnant problem."

You can use "stagnant problem" to describe a problem that is:

* Not being solved: There's no progress being made to find a solution.

* Not evolving: The problem remains the same, without any new developments.

* Lacking energy or momentum: There's no excitement or drive to find a solution.