Qgis: Available WMS layers are not displayed in QGIS Browser

[pathmapper]

Describe the bug
Available WMS layers are not displayed in the QGIS Browser.

How to Reproduce
After adding a WMS with the following URL to the browser with QGIS 3.12.0 the available WMS layers are not displayed in the browser (there is only 1 layer displayed but there are more):
https://www.wms.nrw.de/geobasis/wms_nw_dop

QGIS and OS versions

QGIS version | 3.12.0-București | QGIS code revision | 409bcf8eaa
-- | -- | -- | --
Compiled against Qt | 5.11.3 | Running against Qt | 5.11.3
Compiled against GDAL/OGR | 2.4.0 | Running against GDAL/OGR | 2.4.0
Compiled against GEOS | 3.7.1-CAPI-1.11.1 | Running against GEOS | 3.7.1-CAPI-1.11.1 27a5e771
Compiled against SQLite | 3.27.2 | Running against SQLite | 3.27.2
PostgreSQL Client Version | 11.6 (Debian 11.6-0+deb10u1) | SpatiaLite Version | 4.3.0a
QWT Version | 6.1.4 | QScintilla2 Version | 2.10.4
Compiled against PROJ | 5.2.0 | Running against PROJ | Rel. 5.2.0, September 15th, 2018
OS Version | Debian GNU/Linux 10 (buster)
Active python plugins | ClipMultipleLayers; quick_map_services; scriptrunner3; LAStools; canvas_clipper; savedialog; loadthemall; kmltools; MapsPrinter; mmqgis; pluginbuilder3; vector_tiles_reader; layerGroupFilter; plugin_reloader; realcentroid; mask; MetaSearch; db_manager; processing

Additional context

• With QGIS 3.10.1 the WMS layers are displayed.

• With QGIS 3.12.0 it is possible to add the WMS layers via the "Data Source Manager":
  

• https://github.com/qgis/QGIS/issues/34692 could be related.

[gioman]

Confirmed regression.

[Samweli]

Confirmed on master, working on a fix!

[pathmapper]

This is fixed in 3.12.1, thanks!