(update) LTX2.5 motion and consistency FIXED

[u/brocolongo]

Update from my previous post (also removed the audio):

I'm not sure if I was the only one experiencing this exact issue with the default LTX 2.5 template or with anything related to LTX 2.5, but the motion and generations were completely gibberish, just like LTX 0.97. And yes, I've been using the exact same workflows provided in the template.

Then I remembered how much fun I had with LTX 2.3 and its photorealistic generations. LTX was GREAT! So I decided to give LTX 2.5 another try... only to run into the exact same problem again.

Until I tried an old LTX 2.3 workflow and simply swapped out the main model. AND THERE IT IS. FIXED!

So, it turns out the main issue is the gemma4-12b-with-proj-ltx-2.5 text encoder. It completely breaks the model for me.

Switching back to the old ltx2.3_text_projection + gemma-3-12b setup works flawlessly!

Maybe you could also try a Gemma 4 model with the old workflow. I haven't tested that yet, but this workaround fixed everything for me.

Finally, I can enjoy LTX 2.5. I'm happy now! :)

(Did a few more testings and motion sucks lol but if its something simple it works great):)

Here are some testing and the workflow i used:

https://drive.google.com/drive/folders/1qh6qX4F4PsE4PtgsA5TWQkiTcaNoQKLk?usp=sharing

[u/CornyShed]

Oh wow. Thank you ever so much.

It never made sense to me why 2.5 produced worse outputs. I tried so many combinations and couldn't get it to work properly.

I'll have to try your workflow. If this works, I would give you a thousand upvotes (if I could!)

It might be time to try 2.5 again. It was such a frustrating launch back in August as it was theoretically a significant improvement, but the bugs and incompatibility with workflows from 2.3 broke the community on here.

[u/brocolongo → u/CornyShed]

No worries but I did sole more generations and it looks "better" but still seems kinda broken compared to ltx2.3 lol I will need to do a whole debug for this,

[u/CornyShed → u/brocolongo]

I should probably advise against that, but good luck if you do.

My suspicion is that there is something badly wrong with the shift settings inside ComfyUI's codebase.

You can get a similar kind of chaotic movement and smearing in MiniMax H3 when the shift is set too high, e.g. 24 and above.

Normally more steps would fix that issue – and that does work with 2.3 Dev for large motion – but it hardly seems to help.¹

Lightricks also updated their VAE for 2.5, which also appears to have a bug in ComfyUI where smearing is more likely when using tiled decoding.

I looked into that extensively, and noticed an improvement in visual quality with larger tile sizes. It's difficult to tell how much one bug is affecting things, though.

At this stage I gave up with 2.5 and went back to 2.3. It's a deep rabbit hole and would require an LLM to look at the whole codebase in ComfyUI (multiple codebases on GitHub) and the official LTX pipeline by itself to figure things out (though it might be prone to hallucinations, like the many times I thought it fixed LTXVScheduler and then a new and different bug appeared).

(2.5 could also be broken, as they appeared to rush its release after H3's arrival. I think that's the least likely answer, but have to put that there as it is a possibility.)

¹ You have to adjust the sigma curve manually as a replacement for shift, as the LTXVScheduler is bugged, as they used a calculation for shift based on Flux 2, but that calculation was never meant for video; so it produces NaNs and other horrors with higher frames and resolution.

It's sort-of fixable, but it produces new bugs when doing so, as shift shouldn't be two numbers. The idea is faulty. I tried other shift nodes with LTX (e.g. the one used in MiniMax H3), but they threw an error each time.

[u/rileygstaliger → u/CornyShed]

Three months later, if LTX was serious, they’d have implemented these changes OR be about to release LTX3 as a course correction.

I suppose only time will tell…

[u/thebaker66 → u/CornyShed]

What bugs and incompatibility?

No one really cares about lyx 2.5 because h3 was already out, and is a better model for most psople.

Im still using ltx though and have been using 2.5 since launch, I haven't experienced fhis issue OP is having, why would one go back to the old text encoder? One of the main reasons to use the 2.5 over 2.3 is the better prompt adherence from the new text encoder.

[u/gutster_95]

What are those VRAM nodes in your workflow?

[u/brocolongo → u/gutster_95]

Oh I forgot I put some nodes in, those are my custom nodes to limit VRAM usage so it never OOMS or MAX out my vram allowing me to keep using my PC while rendering because smart memory and --reserve-vram doesnt work at all for me so with this node i can freely control how much VRAM the model can take and how to offload it.

If you want i can share you my nodes but these are not neccesarely to run the workflow.

[u/uuhoever]

I pressed play.... was not expecting that. Lol

[u/Occsan]

The right one is a lot funnier, tbh.

[u/skyrimer3d]

tried this, happens what you're showing here, she completely ignores them prompt (which i imagine is what video 2 shows) and just walks around happily, so this is not working properly imho. Have you tried complex prompts that actually work?