Hi @Pascal,
Working with one of the recent daily builds (Version 6 SR13 (6.13.19021.12581, 1/21/2019)) there seems to be a problem with layer materials (I only tested these).
As soon as a texture image is assigned to any of the slots (Custom Material) : (diffuse, transparency), the material will not save any parameter changes, unless new material is assigned, even if the texture gets removed). Curious if you can repeat it - happens here on every file.
thanks,
–jarek
PS. How to we downgrade to the latest stable SR12 RC ? This is a big issue here now : /
Hi Jarek - look for the installers in
C:\ProgramData\McNeel\McNeelUpdate\DownloadCache
Search for *.exe in there from Windows Explorer and I think you’ll find a recent sr 12…?
Also, I see the bug here as well - thanks for the heads-up.
-Pascal
Hi Pascal, thanks!
I cannot find the SR12 there, only very old ones or V5 ones. Somehow I am missing the SR12s. Is there any download link for the most recent official SR12 RC I can follow ?
–jarek
Hi Jarek - you can edit the material, as far as I can see, from the Material panel- does that stick for you?
If not, try - http://files.mcneel.com/dujour/exe/20190122/rhino_en-us_6.12.19022.16441.exe
https://mcneel.myjetbrains.com/youtrack/issue/RH-50462
-Pascal
Hi Pascal,
The material changes edited via Materials panel stick, but neither the preview or layer material update with these so no, this doesn’t solve it or work as a workaround over here.
May need to use your SR12 link until this is fixed and ditch daily builds - thanks!
–jarek
Hi Jarek - here the changes from the Materials panel are honored but so far I need to jiggle things to get them to register - I’ll poke at it some more - thanks.
-Pascal
Reverting back to SR12 - can’t jiggle now 
… thanks a million for quick help after hours!
–jarek
FYI - The version you sent me link to does not have that issue.
This bug was fixed last night during the dev meeting by @andy and @johnc. A newer build later today should do it. The next SRC of 12 should have the fix in as well once it is out
Thanks, good to know.
I think I officially have to quit daily builds testing… because of that one bug (which you guys knew about anyway) I needed to revert back to SR12 which somehow permanently messed up my display speed when mesh wires are on, making Rhino 6 unusable so far since I lost the ability to work with mesh models, even after installing back the latest build that speed-wise worked just fine.
It’s a risky business and I should have known better than trying daily builds while on tight deadline 
–jarek
Living dangerously, hooked on adrenaline and stress hormones!
Let’s just call it irresponsible : )