I have had the same problem mit woodmart Theme. My graphic program writes into svg file following values:
<svg
width="100%" height="100%"
viewBox="0 0 369 53"
The header builder or the theme does not accept these values. So you had to edit the svg file with a standard editor (e. g. notepad++ or pspad) and changes it to:
<svg
width="369" height="53"
viewBox="0 0 369 53"
like it is also in the orignal file 🙂
Maybe the header design does not say, in wich dimension the svg file should be presented? In the mediathek the 100% svg is automaticly resized to 100x100px. The edited svg file is at 369x53px.
This is may the key to fix it 🙂