RibbonWinForms VS office-ribbonx-editor

But, Ribbon controls have been created which attempt to replicate it in Windows Forms. There are quite a lot to choose from. This is one of the first hits

Have you tried the Office Ribbon Editor? It makes the XML portion very easy to manage. There might be a weird issue with the way you're currently doing it causing the xml to be removed from the file.

By using ribbonX (find it here: https://github.com/fernandreu/office-ribbonx-editor) you can create custom toolbars based on XML, however this can be difficult.

And rather than handcoding the RibbonXML, you'll want a copy of the free Office RibbonX Editor: https://github.com/fernandreu/office-ribbonx-editor

However, I've always just used this FOSS editor. It's a standalone editor, no need for admin rights, and best of all makes editing the file for the custom tab super easy along with verifying your xml is formatted correctly for the change.

I create custom tabs using the new fabric custom UI API and office ribbonX editor, which is open source and makes the life so much easier (I believe this may be the tool you're using), if not you should def give it a try. The tool comes in a pre-compiled version that is compressed. No need for admin rights or anything.

I have a workbook with a custom ribbon (added via XML using the Office RibbonX Editor so that the custom ribbon stays with the workbook). In the Ribbon, I have a few checkboxes true/false, that are linked to cells on a worksheet.

Office RibbonX Editor - an opensource alternative to Visual Studio (expressly for the purpose of creating the customUI file needed to create a custom Ribbon, not an IDE). The README has good information, and links to further resources for creating an Add-in.