I will take a copy of the web site and perform a Warp update to see whether it resolves the issue.
I'll get back to you with the result.

Thanks !

Hi,

Updating the WARP framework was indeed the solution to the issue...
I had version 7.3.14 and went to 7.3.21 (FTP of warp folder to web hosting).

When I compiled LESS, I lost some color changes I made to the template. So when I performed the change to the live site, I did not compile LESS again.
Is there any reason I should have to do this ? Or can I go ahead without ?

Thanks,
Mario

Please never edit the original CSS & customizer styles, because these files will be overwritten when compile less or updating the theme.
Always add your custom style to the custom.css and create a new style in customizer.
www.joomlaplates.com/template-customizing

I have a custom.css with quite some code in it that I added, but I believe the color changes were done through the customizer.
Well, not the biggest issue and easy to resolve.

Thanks for the pointer in the right direction (WARP) for this one !

Happy Easter !

Problem solved.