I have a test page below where I have merged header set for both desktop and mobile and in the mobile view. It is showing the desktop logo not the white SVG.
I turned off all the plugins except for GP Premium and it still did is not working.
Can you check on Appearance > Customize > Layout > Header and check if you’ve set the white logo on the logo setting. https://share.getcloudapp.com/kpu7koer
If not, you can set it there also so the desktop and mobile logo matches.
Thank you for the reply. Yes, I do have a logo set there which is not the white logo since The entire site does not use a merged header or at least at this point. So is there a way like you can with some themes with the customizer or CSS to set a specific logo just for the merged header for all versions not just desktop?