You're very welcome, Pete!

Thank you so much for this wonderful feedback!

Yes, I was aware of your late hours, and I hope that the rest of the project will work out nicely without long evening hours.

I have left the Attribute Manager > Mode > Scene > Simulation> Scene Scale as you had it. (Many times "Scene", but that is the path) Since it was cached, I haven't made any changes. (Yes, I tested it with a 5cm scale, and got indistinguishable results compared to yours. So I left it as is.)

This is perhaps more for after the deadline to explore, but just in case:
There is a little bit of "jitter" in the spline. I have marked the three elements in Pale Blue (layer chips). Since the whole "group" moves. I was not able to place it inside (it would receive twice the motion), so it is on top.
The idea is to produce a copy of the spline, mainly to add the Delay Effector to it, and with Blend to limit the jitter. I'm not clear how that will affect the hand animation synchronization. But just in case things are needed.
https://projectfiles.maxon.net/Cineversity_Forum_Support/2025_PROJECTS_DRS/20251021_CV4_2025_drs_25_SIha_11.c4d.zip
Here is a simple version of it.
CV4_2026_drs_25_ANnt_01.c4d

My best wishes!

Thank you, Pete,

For the feedback, despite your deadline. Yes, "freezing a working pipeline" during production to stay sane is always a wise decision.

Here is the file I saw. As usual, the real judge is in the rendering, not in the editor view.
https://projectfiles.maxon.net/Cineversity_Forum_Support/2025_PROJECTS_DRS/20251021_CV4_2025_drs_25_SIha_01.zip
(This is the mandated cloud I have to use here. Just in case you wonder)
I didn't shared it as I'm not sure you wanted it longer in public (please advice in this point).

I hope my Alembic is not different from yours. Either way, please let me know if there is any time at all for this.

My best wishes for your production

Hi Pete,

Thank you very much for your patience with my security neurosis. But this year, I had three IT security trainings already. Considering last night's Amazon outage, which shut down 2,600 companies, there is no exception... So thank you.

Please have a look here.

As far as I understand your target, the two splines, Cached as well as the Alembic, need to be positioned above the Spline Wrap and above the its Parent Object, so they are not affected. The hierarchy, top to bottom, and priority numbers are crucial. An incorrect position in the Object Manager can cause at least one frame to be lost.
I have also set the Bounding Box of the Spline Wrap to Fixed, just in case, in my exploration. I created the Alembic after I moved it up; the "original Alembic was not in the file.

Please let me know if that works for you.

I noticed that you used 2025.3.3. If you'd like to use another version, I can check. Please advice.

My best wishes for your project

Hi Pete,

For security reasons, I only access Dropbox, WeTransfer, Google, Adobe, or Apple cloud files that are uploaded as non-zip/rar files. Please paste the URL as you did. Sorry for the extra work. So far, I have no clearance for app.box.com, sorry.

I'd be happy to review your file.

Cheers

P.S.: As those things don't let me alone I checked again all (im-) possible options.
As usual, I need to try it.

Here is a little 10-second clip, where I can reproduce it and showcase a click later on how to solve it (fingers crossed that works for you.
https://projectfiles.maxon.net/Cineversity_Forum_Support/2025_CLIPS_DRS/20251021_Timeline_Activated.mp4

In short, rectangle selection does something, but does not fully activate it. When I click on it, all is there. Could that be the difference, why you see it, and I don't?

Fingers crossed that makes it work for you.

Hi entry newspaper,

I can check the layout (Dropbox, Wetransfer, Google, apple or Adobe cloud only, for security reasons. Thank you), but is that problem also showing with the default standard layout? Anyway, I think it is time to check with tech support.
https://www.maxon.net/en/support-center

Yes, you need to open a ticket.

My best wishes

Thanks for the feedback, entry-newspaper.

If you think it is something you did and you would like to test this, delete the preferences.

I have the feeling it needs to be checked by Tech-Support.

Sorry for having no quick answer here.

Thanks for that, entry-newspaper.

Try this:
1
Where it says 'Custom (Attribute Manager)', select 'Custom', pull the menu, and then go back to 'Custom' or try something else for a moment.
2
Next: Copy the Cube and paste it into a new file. Any luck then?
3
There is also a square on the upper right of the timeline, with the arrow pointing to the upper right. When you click it, another timeline shows up.

Have you had any luck with any of these?

I try to gain data here.

Cheers

Hi entry-newspaper,

Thanks for the file.

(Images: max 500 pixel high)

I can change the handles while the Menu is not grayed out. However, I'm on 15.5 with the M1 Max.
I had to update another M1 (which I use more for testing) to 15.7.1 to test your findings, hence the delay in my response.

Works fine here on both. I apologize that I'm unable to confirm it.

Here are two screenshots; some icons appear in specific selections (not just the Keyframes).

See the difference in the Left side selection and the Icons.

Please check with Tech Support.
https://www.maxon.net/en/support-center

All the best

Thanks for sharing your experience, smckenzie.

Sounds good!

My best wishes for your Project