Subfolder disappear when selecting page next to it

[thomas-henkel-ep]

The problem
When selecting option treenew of indexmenu plugin, subfolders of a folder disappear when selecting a page in this folder,

Version of DokuWiki
2024-02-06b "Kaos"

PHP Version
8.0

Webserver and version of webserver
Apache 2.4.54 on Windows Server 2022

Browser and version of browser, operating system running browser
Opera One 122.0.5643.142, Microsoft Edge 142.0.3595.53, Firefox 144.0.2 on Windows 11

Additional environment information
Assume there is the following folder structure in data/pages
├─ [hardware]
│ └─ ...
├─ [labview]
│ ├─ [documentation]
│ │ └─ page1
│ ├─ [lib]
│ │ ├─ [extended]
│ │ │ ├─ page2
│ │ │ └─ page3
│ │ └─ [src]
│ │ └─ page4
│ ├─ page5
│ └─ page6
├─ [tools_extern]
│ └─ ...
└─ [tools_intern]
└─ ...

When selecting page5 or page6 the indexmenu hides the [labview] subfolders and reduces to
data/pages
├─ [hardware]
│ └─ ...
├─ [labview]
│ ├─ page5
│ └─ page6
├─ [tools_extern]
│ └─ ...
└─ [tools_intern]
└─ ...

see this DokuWiki forum post.