Hallo, I tried your plugin, but I get white empty dialog box.

Windows 10 + Sketchup version 2021.0.339

And in Sketchup 2020 dont get nothing dialog box. After restart I get thisr errors:

Error: #<NoMethodError: undefined method each_folder' for #<Sketchup::Layers:0x0000021a38918260>> (eval):758:in GetLayerListEx'
(eval):764:in GetLayerList' (eval):333:in refresh'
(eval):219:in initialize' (eval):1341:in new'
(eval):1341:in initialize' c:/users/fero/appdata/roaming/sketchup/sketchup 2020/sketchup/plugins/zzlab_multitagplugin/plugin.rbe:69:in new'
c:/users/fero/appdata/roaming/sketchup/sketchup 2020/sketchup/plugins/zzlab_multitagplugin/plugin.rbe:69:in main' c:/users/fero/appdata/roaming/sketchup/sketchup 2020/sketchup/plugins/zzlab_multitagplugin/plugin.rbe:85:in class:Plugin'
c:/users/fero/appdata/roaming/sketchup/sketchup 2020/sketchup/plugins/zzlab_multitagplugin/plugin.rbe:6:in <module:MultiTagPlugin>' c:/users/fero/appdata/roaming/sketchup/sketchup 2020/sketchup/plugins/zzlab_multitagplugin/plugin.rbe:5:in module:ZZLab'
c:/users/fero/appdata/roaming/sketchup/sketchup 2020/sketchup/plugins/zzlab_multitagplugin/plugin.rbe:4:in <main>' C:/Program Files/SketchUp/SketchUp 2020/Tools/extensions.rb:197:in eval'
C:/Program Files/SketchUp/SketchUp 2020/Tools/extensions.rb:197:in require' C:/Program Files/SketchUp/SketchUp 2020/Tools/extensions.rb:197:in load'
C:/Users/fero/AppData/Roaming/SketchUp/SketchUp 2020/SketchUp/Plugins/ZZLab_MultiTagPlugin.rb:26:in register_extension' C:/Users/fero/AppData/Roaming/SketchUp/SketchUp 2020/SketchUp/Plugins/ZZLab_MultiTagPlugin.rb:26:in module:ZZLab'
C:/Users/fero/AppData/Roaming/SketchUp/SketchUp 2020/SketchUp/Plugins/ZZLab_MultiTagPlugin.rb:5:in `<top (required)>'