Have a similar issue. I use mac & windows for work and chats are not syncing between both laptops even though using same account.
This exact issue is still happening in September 2026.
My setup:
Desktop:
- Windows 10
- latest Chrome
- ChatGPT web
Mobile:
- Android 16
- latest ChatGPT Android app
Reproduction:
- I have the same conversation open on my desktop.
- I continue the conversation on Android and create several new messages.
- I return to the desktop browser, which still has the stale older conversation state.
- I send a new message from the desktop without manually refreshing.
- The newer mobile messages disappear from the conversation on both devices.
I just lost several hours of brainstorming and technical work because of this.
This is not a cosmetic sync bug. It is destructive stale-client conflict handling resulting in conversation data loss.
The client should never be allowed to submit from stale state without first checking the latest server-side conversation version.
I have also submitted this to OpenAI Support under:
CHAT DATA LOST: cross-device sync failure overwrites newer mobile messages
If anyone has found a reliable way to recover the overwritten branch or prevent this besides manually refreshing every device before sending, please let me know.
Just happened to me too. Same setup: Conversation started in browser, continued on mobile, next day continued in browser → just realized that the entire conversation I had on mobile is simply gone. This is a real bummer. Especially that this issue obviously hasn’t been fixed in almost 2 years …
I experienced apparent conversation data loss caused by a cross-device synchronization conflict.
I had the same ChatGPT conversation open on desktop/web and on the mobile app. The mobile client did not have the latest conversation state / the clients became out of sync. After continuing the conversation from another device, a large section of the conversation disappeared.
The missing section contained several hours of technical work. Some artifacts/files created during that missing section still exist in my ChatGPT Library, which strongly suggests the work existed server-side, but the corresponding conversation messages are no longer visible.
No clue how to restore it.
We accidentally discovered a serious bug in ChatGPT, which we named “Collapse.” This is our own working name, not an official OpenAI name.
Under certain conditions involving a problematic or incomplete file upload, a conversation can appear to roll back to an older state: newer messages disappear from the visible conversation, and ChatGPT appears to continue from an outdated version of the chat.
We specifically tested this on Android, and in our controlled test scenario we were able to reproduce the issue manually with a 100% success rate. However, we do not know whether the bug is limited to Android, as we have not performed the same controlled tests on other platforms.
Initially, we reproduced it by closing the app while a file upload was still incomplete. Later, we observed a similar occurrence without closing the app: a video upload reached almost the end, failed immediately before completion, and the conversation subsequently entered a similar rollback state. The exact technical cause remains unknown.
In our cases, logging out of the ChatGPT account and logging back in restored the current conversation state. This is an observed recovery method from our tests, not an officially confirmed or guaranteed fix.
We also checked whether this problem had already been reported. We found no official OpenAI name for this specific scenario, although other users have previously reported similar issues involving disappearing messages and outdated or unsynchronized conversation states. Therefore, we are not claiming to be the first people to discover this general type of problem. What we independently found was a specific Android scenario that we were able to reproduce consistently.
We have already reported the issue and our test results to OpenAI Support.