Screen Sharing Invitation grayed out

According to this article : If you can't sign in to your iMessage account or FaceTime on your Mac - Apple Support

Reset NVRAM

In case the issue is related to any of the settings stored in NVRAM, reset NVRAM on your Mac.

Check for third-party software

If you installed firewall, security, VPN, or other third-party networking software, make sure that the software isn't blocking any of the network ports used by iMessage and FaceTime. If necessary, disable the software and then try using your iMessage account or FaceTime again.

Also , enter in User library : macOS Sierra: Library folder

Find a folder Preferences > drag and drop com.apple.imessage.plist to the desktop , restart the machine , and open iMessage , use the application .

Enter once again in User Library verify that com.apple.imessage.plist is recreated , drag and drop the plist from the desktop to the trash and empty it .

Why are people so keen to reply with unrelated things, earning points?

No one said there is a login problem. We are all logged in just fine. How else should we be able to chat with each other. It's only Screen Sharing that isn't available.

Read this article : Messages for Mac: Share your screen or another user’s screen in Messages

When you share a screen with Messages, you and your friend can work together on the shared desktop. When you start a screen-sharing session, Messages automatically starts an audio call. You can perform actions such as opening folders, creating documents, and copying files by dragging them from one desktop to another.

If the person you’re sharing a screen with uses a different Apple ID in Messages than they use to sign in to iCloud preferences, you must have a contact card for that person. The contact card must include both Apple IDs—the one they use to sign in to iCloud preferences, and the one they use in Messages. For information about creating contact cards, see Create a contact card.

Important: When you share your screen, your friend can request to control your screen, which gives your friend the same access to your computer that you have. Grant screen control only to people you trust. If you share your screen but don’t grant screen control, your friend can highlight areas on your screen by clicking them but can’t control your screen.

Share your screen or a friend’s screen

1. Select a conversation with your friend, or send your friend a message.
2. Click Details in the Messages window.
3. Click the Screen Share button , then choose an option.
   • Share your screen: Choose “Invite to share my screen.”
   • Share a friend’s screen: Choose “Ask to share screen.”

When the screen-sharing request is accepted, the Screen Sharing app opens. For information about using the Screen Sharing app, see Screen sharing overview.

Respond to an invitation

When someone invites you to a screen-sharing session, a small window appears notifying you of who sent the invitation.

• Accept, decline, or block the user (hold the pointer over Decline, then click ).

Screen sharing in Messages is independent of screen-sharing settings in System Preferences. You can share screens using Messages even when Screen Sharing is deselected in the Sharing pane of System Preferences.

It's exactly what we do. Step 3. is what doesn't work. The Screen Share button is disabled and so is the menu command.

Please consult in Apple support why the screen share button is greyed , I can not reproduce the issue in my system .

As per my knowledge the message application is not working .

In user library > preferences > drag and drop the plist to the desktop , restart the machine , open messages and see if it works .

And according to the article that is for Mac OSX Yosemite : Messages (Yosemite): Audio chat, video chat, and screen-sharing requirements

Internet connection speed (upstream and downstream)

To find your connection speed, contact your Internet Service Provider (ISP), or refer to the documentation from your service provider. The speed listed in the documentation is the maximum possible speed; the actual speed may be lower.

Hi,

Leaving aside the fact that  certain Apple IDs can be used as AIM Screen Names and the App used to be able to do this Over AIM as detailed above.

It could be a Login issue of sorts.

IF...

One end is in Messages > Settings > Accounts and the iMessages account and the only active ID to Receive (and therefore the Send Drop Down is effected) is the iPhone Number will not be able to Share Screens.

That is to say that the Apple ID is logged in  but the Send And Receive items are reduced to just the iPhone number.

Technically this make iMessage Syncs work as iMessages addressed to the Apple ID will show up as the iPhone Number as ID will show them.

The second potential issue related to this is you can't tell if the Apple ID is actually logged in until the Apple ID is the only Receive/Send option (the iPhone Number is deselected) and you try to send (manually enter your iPhone Number as it will not call up the My Card info as you are not expected to call yourself)

Of course the issues detailed in this post also have to be tested at the other end.

Example pic of Apple ID as AIM Screen Name for Messages:-

8:18 pm      Thursday; May 11, 2017