Can no longer move chats into projects

Last days had the idea to organize my old chats, so I created some projects and started to move my chats.
This works great, but suddenly there's an error message 'Das Projekt des Gesprächs konnte nicht aktualisiert werden' (de)

<img width="609" height="758" alt="Image" src="https://github.com/user-attachments/assets/a9b3cdf9-43cf-407f-b683-6dd37f2a1e32" />

<img width="898" height="106" alt="Image" src="https://github.com/user-attachments/assets/b2530cbf-48d4-489a-983f-85b2e2b4161d" />

Opened the Project and the Chat is missed

<img width="599" height="379" alt="Image" src="https://github.com/user-attachments/assets/f7943617-f349-4aea-95df-548ef967af5d" />

Hovering on list entry and the Chat is connected correctly with Project Info

<img width="726" height="378" alt="Image" src="https://github.com/user-attachments/assets/dae4a59a-f1ab-4f64-8b08-9d1b76833e06" />

Tried with different Chats or Projects - always the same
waited and updated to newest ChatGPT version - always the same
las one was 26.810.41047