Which error bar do you mean? Can you post a screenshot?

Threat Plates does not show an energy bar per se. It shows some bars (like healthbar, castbar) which you probably don't mean and also the resources of nameplate units which could be energy, but most of the time is something else.

My UI is chinese, you can reference below image. It should call resource bar.
D:!MyCloud\Dropbox\Temp\WOW_AddOns\JPG

You can reference below youtube video or image about the resource bar.
It will always stuck at 50%.

Youtube Video URL.
https://youtu.be/brI_mpEvqf0?t=172

I can see what you mean. It seems that the Ressource widget (you were correct) is not updated, i.e., does not process the events that are fired when the resource changes. I will look into it.

Thanks. Hopefully, you can resolve this issue soon.

I was able to find out why it's not working. The event registration (events when the resource, e.g., engery, changes) is not done correctly. I don't know if there was a recent change, but it does no longer work as it used to. I will need some days to fix that.

I think I was able to fix the issue, although I had to remove soft-target support for the Resource widget. But it never worked anyway, I think. Here's the fixed version:

https://drive.google.com/file/d/1QVWVPFCod4Z7fD_K9CR-BnZ7j70tErw1/view?usp=sharing

Thank you, I ran a test.
The initial target works, but when I switch to a different target, the bar stucks then disappears and doesn't show up again when I switch back.

Interesting, that does not happen for me. There seems to be a setting that causes this.

One question: do you have soft-targeting enabled (for friendly and/or enemy units)?

The setings as below. I test normal boos-1 of The Rookery.
You just need to keep some monsters before fight with boos-1 then you can switch to monsters then back to boos.
BTW, I can record video on youtube for you later.

I record the video with audio to explain the issue, you can reference below Youtube video.
Hopefully, it can help you on this issue.
https://youtu.be/0UnW18-FtC8?t=43

Thanks for your video. That helped a lot. I was now able to identify why the resource bar is not shown and I was able to fix it. But in the process I found another bug - basically "Boss battle special enerty" is not working or not working as intended.

The above boss, e.g., uses ENERGY as a resource (like Rogues or Druids), not alternate energy. This now results in a solution where I cannot really restrict when to show the resource bar and when not. The above boss, e.g., is an elite with ENERGY, but so are all other mobs (with MANA) ... The only idea I have is to remove the resource bar if it's an NPC with mana.

I think I found a way, but I need a bit of time to make it workj. The boss loses its alternate energy mid-fight (when it flies to the center) and switches to plain energy (non-alternate) and only gets it back after it flies back again. So, I need to add some kind of detection for this.

Thanks to your help, very appreciated.

Yesterday, I used WeakAuras to implement a resource bar that only appears for my target.
My goal is to always display the boss resource bar, even when I switch targets.
However, I haven’t been able to achieve this with WeakAuras. Maybe you can reference it as below RUL.

https://www.dropbox.com/scl/fi/77vzk6e2w66hiul1ltvv6/TargetResourceBart.txt?rlkey=hijbw5u5jk69ph1eyinn22tn2&dl=0

Here's a version that should work now: https://drive.google.com/file/d/1whwcKVzjmwI3mPynh_HRV8QVuNyDoMoU/view?usp=sharing

I tested it with the above boss as well as visibility settings with different kinds of units (as there was a bug as well), and it worked fine.

I just test it, it is more better.
But it had a issue, when I switch target, the boss percentage of resoruce bar will stuck (stop in previous value).
When I switch back, it will jump to correct percentage then keep going.
Is it possible to let percentage of resoruce bar keeping going even I switch target?

Can you explain that in a bit more detail? When you switch target, the resource widget should be shown on the new target or hidden, if you don't target another unit or a unit that does not have a valid resource.

Because of this, I don't understand the "will be stuck" part. Does that mean that you have targeted the boss, then you switch to another mob, but he resource bar is still shown on the boss and not hidden?

Below is more details about questions.

1. When you switch target, the resource widget should be shown on the new target or hidden,
   --> It will depend on the new target has resource or not, in this case new little mod has no resource, so does not need to show resource widget on new target, the boss resource should keep shown and progrss, but this case boss resource progrss was paused.

2. Does that mean that you have targeted the boss, then you switch to another mob, but he resource bar is still shown on the boss and not hidden?
   --> Yes, but progress value was paused.

3. You can reference below Youtube video what I record about the issue.
   https://www.youtube.com/watch?v=NUD-gZUL4sY

So it's still buggy. Hm. Keeping the resource bar updating while you are not targeting the mob is more complex as I need to register events differently (not register to target, but the actual unit like nameplate1, nameplate2 and so an and also change that everytime you switch the target).

Also, only hiding or switching the resource widget when you target another unit with a valid resource is more complex.

So, I will first try to fix the actual bug. That should work as designed first.

Maybe you can only focus on boss fight to monitor boss1, boss2, boss3, boss4 ..., only for boss resource.
Most cases, we need to monitor bosses resource to do different reaction, like Dragonflight Raid - Council of Dreams, that have 3 bosses, we need to monitor each boss resource, you can reference below URL.

Dragonflight Raid - Council of Dreams
https://www.youtube.com/watch?v=D7sLoufzq7g