New in 2017.3f1 and this is a 100% blocker to shipping any of our games - it renders all UI broken if you ever disable any of it at any point at runtime. In many places we use tricks to hide UI without necessarily disabling objects, but there are still SOME places in every app where disabling is appropriate, and as of 2017.3f1 this breaks ALL of those places. Was not present in beta 10. Complete demo:
Bug submitted with repro project. The repro project is 2 empty images. Just try as in the video.
Case #974768.
Ah, just saw this other post on the same topic. As this demonstrates, the problem is even more severe than described in that thread.
Yes UI is broken. When we apply prefab changes our prefabs are completely messed up.
LeonhardP is probably going to ask for the Case number. If you want to speed things up, you could update your initial post with it 
I guess the f part of the release ends in -ed Pretty frightening bug.
Thanks for the reports, and sorry for the inconvenience! We’re aware of the issue and working to resolve this as soon as possible.
Thank you for checking the forum and giving a helping hand even at weekends!
Ditto - much appreciated.
Seeing something similar. In game when enabling a panel and then disabling it it doesn’t go away. SetActive(false) not working correctly.
Yes in Editor you can just resize game view and it will go away. Seems like ui gpu buffer is not cleaned?
when I see these kind of bugs reaching a release candidate it gives me goosebumps, I always avoid final releases of unity and wait at least for two patches ahead of the official version, last time I jumped into a new fresh version with 2017.2 I ended up with constant random crashes, random errors thrown in the console, basic editor functionality broken like trying to rename a game object or moving multi selected objects working so bad. how do these basic bugs survive through many beta stages, automated test suites, internal unity human testers and people beta testing over the world, I have no clue.
Yeah it does seem crazy from the outside. I’m interested in why the UI keeps going wrong even though it doesn’t seem to be in active development?
aaaah,… so happy it wasn’t my code that went bonkers… now, should I wait for update or downgrade project…
That’s probably why actually. Complex systems you change one thing and it often impacts other stuff only indirectly related. And without good test coverage it can easily go unnoticed.
This will be fixed in the next RC.
When does that drop? I am in like hot water now. I had to switch to Collaborate so VS would stop breaking our scenes script connections for our mainly UI driven project and it warned me to sync my version. I recommended we update to 2017.3 as i had to download anyways. He did and spent an hour trying to squash bugs and fired a warning shot my way. Now this…boy I got me some crow to eat… But I need those danged 2 billion indices meshes for engineering CAD imports.
Slightly off topic but what issues did you have with your script connections?
Holy mackerel. I just updated to 2017.3 hoping to get around the UI performance regressions in 2017.2. Man how this kind of thing gets past beta testing I have no idea? No one thought to test enabling and disabling a UI element? Very much looking for a patch fix for this.