Using the steps listed by animagic I am also able to reproduce the problem with the Timeline.

I have this same issue and I have a deadline to meet ( well had a deadline to meet) . I have just waited for the darn indigo to be fixed which is fixed now only to encounter this new timeline issue the following day . I have purchased the software about 2 weeks ago and I have not yet been able to use it properly due to all the bugs . I run the risk of being fired from my job as i now cannot reach my deadline. Probably (well hopefully) wont actually lose the job but it still makes me look like a fool . 

Charachters are in the timeline list but not in the timeline itself. Does not matter if it is a g3 g5 or whoever. Nothing there 

This as a simple procedure that shows some of the erratic behavior of the timeline (this copied from the forum, so I hope the image links work):

Note: Make sure that Object Related Track and Open Same Track Types are checked when performing the procedure.

1. Create an empty project in 6.52 and save.

2. Load the empty project and add Christian. This is what I see in the timeline (which are not the expected default tracks):

http://forum.reallusion.com/uploads/images/3a09fd9b-a14a-4263-a0d9-53dc.png

3. Save the project and load again. The timeline will be as shown above with Christian included, although he is not selected in the scene.

4. Add another Christian. This is what I see in the timeline:

http://forum.reallusion.com/uploads/images/0699d6e8-893b-47df-81aa-ec60.png 

So even though only the new Christian is selected, both of them show up. Also note that a Shirt is included (which belongs to the first Christian), which shouldn't be the case.

5. Remove the two Christians and the shirt from the timeline (so only the Project tracks are there).

6. Make sure the avatars are not selected in the scene, and then add another Christian. This is what I see:

http://forum.reallusion.com/uploads/images/3d6f9eb3-b130-431b-a930-0603.png

Even though the third Christian is selected in the scene, he doesn't show up, whereas the first two do with yet another set of non-default tracks.

There are many more variants that can be dreamt up, but I hope this shows at least the weird behavior of the timeline for avatars.

I've sent a link to a project that shows this behavior to feedbacktrackeradmin@reallusion.com .

It works fine in v6.51, but not in v6.52.

For those who want to try, the link is: http://www.virtualrealist.com/uploads/timeline_issue.zip .  

(There's a mirror in it, so run under DX9 for full enjoyment. This is unrelated to the bug.)

It is not quite clear what causes the issue. I created a test project in 6.51 with one avatar, which worked fine in 6.52. Then in 6.51 I created a project with an avatar and a camera. This also worked in 6.52, but after saving and reopening, the selected avatar showed in the timeline, but the default tracks were not opened (Collect Clip, Transform, Motion). It may be difficult to reproduce, but the problem is there, as can be seen from the project I provided.