It is not normal. You need to be able to see the screen so that you can terminate the connection if you don't like what is being done.
Are you sure it was Adobe support?
Did you go here:
The only time that it might go black is for a second or two when a new graphics driver is being installed.
Yes, I went through the Adobe help section and it was a secure https: page.
Try again with a different agent.
Just a note: bad guys can use https too. It is odd. Do you have the URL they used (it should be in browser history). Was it something.ADOBE.com/something?
Thanks for the help. Can scammers use an encrypted URL? Sure. Do they? Not really. I connected with the support agent via the adobe domain. I received and downloaded the transcript following our interaction and I am getting followup emails (due to my quick disconnect) from firstname.lastname@example.org.
The agent was undoubtredly an Adobe agent.
I emailed Adobe via webform and ask that they review the case.
Log-in to your Adobe account below and check Support History panel.
If this was a legitimate session with Adobe, there should be copy of your case there.
I did and there is. The support case remains active.