Blank xml sitemap

Hi, I’m pretty new to wordpress so I’m probably missing out on something small or doing something really stupid.
I set up yoast yesterday and connected it to the search console. Everything was fine, showed the sitemaps etc. Did some more work on the site and this morning I checked the search console and there was sitemap errors, checked the sitemap through yoast and all I got was a blank screen. I checked the articles and videos online and still can’t figure it out.
https://casafinders.es/sitemap_index.xml
– I disabled all plugins except yoast and tested it
– There’s no source code showing on the sitemap
– Cleared Cache, disabled and enabled yoast
I did read that I should clear the static sitemaps in ftp if there is any but I haven’t a clue how to do that. I have a list of sitemap files in my ftp but dont know which one it is or what to delete. https://snag.gy/XFuqhl.jpg

Any advice would be greatly appreciated, i’ve been working on this for ages. Thanks !

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