This is the backtracke for deleting a whole particle, then Undo (cannot reproduce an Undo crash if I only delete a particle key...)
There, some ParticleCacheKey is broken...

Blender, you keep confusing me.

Can confirm

Then it's still a UI bug. Because if the unit scale only affects the UI, then changing it should affect how the gravity is displayed in the UI.

As mentioned by @LazyDodo (LazyDodo), this is working as designed currently. The unit scale only affects the UI. We might change this at some point, but for now this is not a bug.

Thank you for the confirmation and the added information about edit mode effects. I think the object setting of flat/smooth shading is key - and that NVIDIA cards are in place. Those are the two salient aspects of this bug. People without an NVIDIA card cannot observe or confirm this bug.

More than a week without reply or activity. Due to the policy of the tracker archiving for until required info/data are provided.

Hi Garry,

Ok, thanks so far, I will go on trying on Sunday since I am travelling right now ...

Hi Imre,
At first glance, I see nothing unusual in system-info_imrevarga.txt. I need to spend further time with it, but not right now - I'm off to my job and won't be home again until quite late tonight - 22:00 zulu or so.
It seems that when you set mesh smoothing to flat, the simulation runs properly. (Here, linux/amd card, smooth/flat is irrelevant. The simulation runs correctly in both settings).
That suggests a workaround: First, set mesh smoothing to flat, then bake the simulation - in the cache settings, Particle properties, click on the "Bake" button and let the bake run for the full length of the animation. This is similar to what @Philipp Oeser (lichtwerk) proposed (Delete cache, set smooth off, Bake, test animation in the timeline - new step in bold). I propose that this approach will at least give you a sane cache of the simulation to save and work with and you can move forward with your project. If it does, I'd appreciate a confirmation here. Thanks!

OKi, lets close this then, its unlikely to be considered a bug atm...

Thanks that solves my problem, i wasn't aware there was a work around like this.

Thank you for your work so far,

@Imre Varga (imrevarga)
Similar to @Philipp Oeser (lichtwerk), I can confirm your observations up to, but excluding, your last step:

changing settings, clearing cash ... all to no avail

I do not have that issue here. Changing settings clears cache. Baking sucessfully caches a new simulation that shows none of the issues you report. Particulars:

1. I temporarily cleared the Dynamic Hair checkbox, which cleared the cache loaded with your file.
2. Then, probably unnecessarily, ran the animation with Dynamic Hair unchecked, just to satisfy myself that there were zero frames cached in memory.
3. Finally, I restored the Dynamic Hair checkbox and baked all 100 frames. Blender reported a cache of 100 frames, consuming about 25.2 MB

This gave me a clean animation. See T68681.mkv Compare with the animation made with your original file and its original cached data. See T68681_original_cache.mkv
To make these animations, I modified your file slightly: I put a damped track constraint on the camera so that it would follow the head.

Oh dear. Keyframes do work after all.

Sorry - Blender info here: Broken: version: 2.80 (sub 75), branch: master, commit date: 2019-07-29 14:47, hash: rBf6cb5f54494e
Worked: (optional)

Hi Philipp,

Cannot reproduce in a simple file [can animate, keys stay there, can change key values etc., all working fine]

I installed previous nvidia driver but the bug persists in all windows 10 64bit Blender versions.

Forgot to say that in linux ubuntu os did not find issues and seems to be more stable and faster with everything.

I had similar unstable issues with windows 10 v1903 and gtx 1070.

I tried everything, bake, delete bake, bake again, go in and out of edit mode, change settings ... just doesn't work. There is a suspicion that it might be related to the RTX2070 or the latest driver of that since I also get the following issues:

Cannot really reproduce, if I rebake (or change any setting -- which also clears the cache), everything is fine...

T67958 might be related, will check

Confirmed, 2.79 has the same issues...

@Olivier Maury (omaury): I assume this can be closed now? (from reading this, all issues seem to be resolved?)

No, this is still an issue in 2.80.

@stewie mazen (stewie) you can check it youself, just dowbload Blender 2.80 Stable from here

In my tests here I just cleaned the cache and the new frame rate works as it should. What happens is if you cache rigidbody at 24fps and then change the frame rate to another value like 60fps the playback will use that cached frames at 24fps and playback that cache with the new 60fps, resulting in a faster playback only on that cached(at 24fps) section of the timeline. that's why you should clean your cache (just changing some physics values) when you change the frame rate of your project.
What could help here is if you change the fps value it could clean the cache for you... but I'm not sure if it "should" clean the cache...