TYPO3 Core

Presets: I created a blank new TYPO3 (10.1.0) project, inserted a page (defined as root page) and in this page, I added a sys-folder.
Error: Navigate to the sys-folder, add a new record (tested with several record types, error occures independent of record-type, so try to add a new sys-category). Save (and not close) the record, well done. Now, add a new record with the "+ New" button in the button-bar. And now, TYPO3 misses the current storage (in our case the sys-folder) and want to store the second record on the root page (ID=0).
Note: Some records are not allowed to insert on ID=0 (for example page content) and an error is thrown: "1: Attempt to insert record on page '[root-level]' (0) where this table, tt_content, is not allowed"