Hi @anthony.gls
The width set to 100% doesn’t seem that the table will take 100% space.
If you have fewer columns table may book itself the space, but do not use it. It will then expand if you pass more data or use colWidths.
But what looks like a bug is that you said that rowHeights do not apply. I created a demo using the latest version here Handsontable example - JSFiddle - Code Playground and it works (row height is 50px).
Could you prepare a demo where I’ll be able to replicate the issue? Maybe mui is altering Handsontable’s CSS settings (first thought), as you predicted. If you could prepare a demo I’ll check it.