Items set to Visible=false are being shown when tabbing inside TabControl

Question

So I am making a new project and I am using a theme for the first time (MetroSet). I currently have 30 buttons in a MetroSetTabControl tab all set to Visible=false. When I first launch the application, all is good. If I tab over to the 2nd tab, then go back to the first, all buttons are now shown.

Any ideas why its doing this, or how to resolve?

See GIF below

Theme Set Being used: https://github.com/N-a-r-w-i-n/MetroSet-UI

Steps to replicate:

1. Create a new Windows Forms Application project in Visual Studio and install MetroSet_UI via nuget:

   Install-Package MetroSet_UI
   

2. Create a MetroSetForm and insert a MetroSetTabControl with 2 tabs

3. Add 1 or more MetroSetButton to index 0 and set them all to Visible=false.
4. Debug application starting on index 0
5. Toggle to index 1 and back to 0