"seem to not" is a grammatically correct and usable phrase in written English.
You can use it when you want to express that something appears to be false or untrue. For example, "This seems to not be the case."
"They seem to not like spinners very much.
The provided behavioral and structural diagrams seem to not being sufficiently capable to represent all relevant information regarding mechanical systems.
We seem to not get those hits until a little later in the game.
Nonfatal casualties seem to "not have the political punch that fatal casualties do," Mr. Kriner said.
And we in the industry seem to not be able to do that".
"We seem to not have the ability or the willingness to do that right now," he said.
Is there a source of money for working college students, who seem to not qualify for anything?
"Both experiments seem to not be working," said Dan Rickman, who wrote the paper along with his colleague Hongbo Wang.
Here in Washington, we seem to not have as high an opinion of ourselves as Forbes does.
When things seem to not meet my expectations, I let go of how I think things should be.
He later interrupted a series of questions with: "you seem to not be happy with the answers I am giving".
