Web version map closes unexpectedly

1. On my ipad-2 with iPadOS 26.4.1, I go to https://app.mindmanager.com.
2. I sign in with my mm account.
3. I create a new rightmap with empty content.
4. I enter a title for the central topic.
5. I add a subtopic and give it a title.
6. The document is closed automatically.
7. After reopening, I see the content I entered with exception of the last addition.

Thie happend with Chrome browser.

When using Firefox it happens already after step 4. The system then displays “websocket error”.