I can confirm this is currently happening to me too and it is extremely infuriating.
7 Likes
I had to rebuild my entire game without unions lol.
4 Likes
This happened to me a few times and I realized that it only happens when I’m not connected to the internet or when I’m connected but there is no internet access.
Try to close the studio, reconnect to the internet and open the place.
Hope this helps!
1 Like
Please always include place/asset links in reports like these. This is part of the Steps to Report a Bug that you need to read before posting your bug report.
From what I’ve heard, unions can become corrupted. In the past, I’ve also made a thread alike to this, however, the unions just vanished - didn’t appear as blocks. 
As of right now, it looks like you’ll have to recreate it again - which honestly sucks! I hope this issue gets fixed soon!
4 Likes
Sorry about that I’ll be sure to do that next time. I’ve already started over and built the game without unions. Sorry for the inconvenience.
Internet is connected at high speeds so it shouldn’t be an issue.
1 Like
This issue has happened again to me. All I did was publish, leave and when I came back the next day, some of my unions were gone. If an admin goes in to check it out, it’s Workspace.BrokenUnions
Luckily I’m mostly using parts however this sucks. Here is the place I’m working on.
Im also experiencing this. When i try to negate a corrupted union, i get this message:
“Something went wrong. CSG returned error code -25. Please file a bug report, preferably with a file containing the problematic object(s)”
I hope roblox is working on fixing this bug.
3 Likes
I’ve been using a lot of wedges, gap fill and triangle plugin instead of slicing. I hope that helps you get by until they fix it.
1 Like
Been getting this issue too, its really annoying!
Roblox PLEASE PLEASE Fix this! This makes CSG v2 useless to me as I get corrupted parts constantly when I save and have to revert back.
4 Likes
Did you union multiple clipping parts on the same plane?
1 Like
Multiple unions in my place disappeared when reloading the saved file after receiving this error (including the union in the screenshot, which is the sunray-looking likes above the negated part)
This was after months of no longer having the issue, and the first I’ve received an error like this.
4 Likes
This has happened to me for the first time yesterday.
I’ve had the exact same problem two times. The first time it affected a door which was a union, second time(today) it deleted basically half of my build when I published it. It’s so frustrating having to re-build everything from scratch. I have provided before and after photos of the unions when I uploaded them(this is the most recent one).
Before:
https://gyazo.com/cf2446e6f6de6f2f02e3d8ff5212090b
After:
https://gyazo.com/aa8e03ada22edbb4a561c7b5245a646b
This is making me pretty upset considering it has happened more than once and with multiple items which took me a while to make. I hope Roblox can look into this and hopefully provide a solution.
2 Likes
I’ve been having the same issues. I started a project which of whom requires a lot of unioning. Took me 6 hours to make, then I save and publish the game, then rejoin 20 min later… and this happend.
Before
20 min later
@buildthomas
The Game
https://www.roblox.com/games/3296945695/DeIusivelys-Place-Number-73
1 Like
A temporary fix until Roblox fixes this dumb and obvious corruption issue would be to Disable CSGv2.
7 Likes
This pissed me off this needs to be fixed asap
2 Likes
Since i’ve been seeing seeing people having these “vanishing union” issues, i’ve been importing my unions as meshes before I close studio. Nothing has happened to me yet so this could possibly be a temporary solution for some?
1 Like
Please refer to: