When we were there 2 weeks ago, they were absolutely enforcing the FP+ times. They were not allowing anyone to enter the FP+ line early - not even by a minute. I cannot speak to whether or not they were allowing people to enter the FP+ line after their FP+ window ended, as I didn't encounter that scenario first-hand. But, based on my experience with the early people, I gather they would not let you enter late, either.
In a nutshell... you have a one-hour window in which to enter the FP+ line - no more, no less. If the Mickey Scanner turns green - enter. If the Mickey Scanner turns blue - no entry.
And, yes, people were arguing with the CM about why they should be allowed early entry into the FP+ line... and, no, the CM did not back down.