It now possible to sync assets through the editor and this ticket is not relevant.
If a user syncs to an asset through the editor (right-clicking it in the Content Browser and selecting Sync), the asset will not update until the editor is closed and reopened.
Note: This issue is new to 4.9 as it does not occur in 4.8
Edit MattK: It is NOT expected that you are able to sync to an asset that exists in memory so do not attempt to fix that as it is next to impossible right now.
1. Create a blank blueprint project and add 1 blueprint of the Actor class called "TestBP"
2. Add the project to Perforce (Move the project into a Workspace's directory, navigate to the Workspace in Perforce, right click the project's folder, select "Mark for add". After this, you should be able to submit this change which will add the project to Perforce.
3. Have a second user sync to the project through Perforce.
4. Have both users open the project
5. Have User "A" open the TestBP and add a variable called "First Variable"
6. Have User "A" connect to source control and save TestBP (It should ask you if you would like to check it out, if so, hit yes) and then check TestBP into Perforce (Right click the TestBP in the Content Browser and then choose Check In under Source Control)
7. Have User "B" connect to source control in the project and sync to TestBP (Right-click TestBP in the Content Browser and choose Sync under Source Control, you may need to select Refresh before this shows up.)
8. Have User "B" open TestBP.
Result: First Variable is not there for User "B"
Expected: First Variable is visible
Head over to the existing Questions & Answers thread and let us know what's up.