Renaming a page used to work fine in version 0.4.2 but ever since the 0.4.3 update, it stopped working completely. When renaming a page using the new way, the page will show the changed name but the linked references are not updated accordingly. More importantly, after returning to the journal and going back to the same page, the new name disappears completely and the page reverts back to its old name. The same bug is still present in the 0.4.4 update.
I noticed that the error occurs only when trying to rename pages with Nested Tags/Pages in them. For example, the new rename functionality would work to rename [[Hello]] but not [[Hello [[World]]]]
Unfortunately, the bug seems not to be fixed anymore in 0.5.1.
When I try to rename a page (in this example “2.32 Musik” to “Musik”), the name change does not work. It is strange though: sometimes it works, sometimes it does not. I haven’t yet found a logic to this.
Your demo just indicates that you have a page [[Musik]] existed, so a merging will be done after you confirmed. If not, this might be a bug we would like to fix, then please file an issue on Github.
BTW, would you please try to re-index the graph, and see if your problem still exists?