Hey @artsabord I noticed that nobody replied to your query. I faced a similar issue and I found a temporary solution (it’s not the best one thought).
Did you, by any chance, change the link colors in the Customizer to white? I had done that because I wanted to change the link colors on some pages to white, and it turns out that it changed my mobile (hamburger) menu to white too. Since your header background is white, your menu is probably not appearing because it’s white on white.
Navigate to Customize> Theme options > Colors
Under Link Color, you can change the color to a darker color and hopefully the menu will appear. The only downside is (which happened for me) that the font of links on other pages will change to that color too.
I’m still trying to find out how I can change the menu color in isolation because I want to change link colors on other pages to white. Until then, if you want a quick fix and don’t mind the font color of links on other pages being the same, you can try the solution above.
Hope this helps.
P.S. I’m a newbie at this. So take this advice with caution because I don’t know if it will cause issues for your website.