Header disappears

Since you are using a commercial theme, we can’t tell you how to deal with it. Apparently it also generates faulty HTML code, the cause of which lies somewhere in the theme’s files, which nobody here knows or can know.

The only advice would be to look for another theme. I think the view you currently have could also be recreated with the current standard theme TwentyTwentyFour – but also with many others.

Hi threadi, as I said my theme is no longer supported so I cannot ask them. Also, my css code is particular to this theme so changing to another theme does not work. I thought it may be a conflict with WordPress or WooCommerce updates, but as bravehound.co.uk is still working it is not that (both use Intuition Pro and WooCommerce)

I already understood that, otherwise I would have referred you to their support. The output in the frontend is determined by the theme. And yes, it might not be (or no longer) compatible with WordPress or other components of your project – but nobody can judge that here because nobody knows your theme. Please also note the information here: https://www.ads-software.com/support/guidelines/#do-not-post-about-commercial-products

If you would like to make adjustments to this and your theme no longer has support, then you can look for someone who can support you here, for example: https://jobs.wordpress.net/

Alternatively, if you use another theme, you can of course implement your desired views there again. Of course, this involves a certain amount of effort. However, it would be questionable how long your current theme will be compatible with, for example, WordPress or the PHP version used by the hosting company, which is why you either have to adapt its programming (if necessary with the help of someone) or use a different theme.