Server Error 500 if post contains elements

Hi there,

I urgently need help with my website. I’ve been looking for the problem for ages but haven’t been able to find it, so I hope someone here can help me.
My problem is this: whenever I edit a page created with Elementor and then try to save it, I get a 500 error message and the page is not saved. I also find it strange that every single text element I click on in the editor is slightly grayed out during further editing. I can edit the content, but it is not updated and displayed. I then experimented a little and found that I can save the page when there is no content on it. As soon as I add a grid layout, an image, or text, I get the 500 error again. What I also noticed when looking at the console output were the following error messages:

TypeError: Cannot read properties of null (reading 'parentElement')
    at ToggleIcon.apply (checklist.min.js?ver=3.32.4:3:47938)
    at ToggleIcon.run (web-cli.min.js?ver=3.32.4:3:147151)
    at Commands.runInstance (web-cli.min.js?ver=3.32.4:3:27842)
    at Commands.run (web-cli.min.js?ver=3.32.4:3:27684)
    at checklist.min.js?ver=3.32.4:3:50264
    at checklist.min.js?ver=3.32.4:3:34117
    at Generator.<anonymous> (checklist.min.js?ver=3.32.4:3:3766)
    at Generator.next (checklist.min.js?ver=3.32.4:3:48428)
    at asyncGeneratorStep (checklist.min.js?ver=3.32.4:3:39506)
    at _next (checklist.min.js?ver=3.32.4:3:39738)


Failed to load resource: the server responded with a status of 500 ()


web-cli.min.js?ver=3.32.4:3 
Object
error	@	web-cli.min.js?ver=3.32.4:3


web-cli.min.js?ver=3.32.4:3 Document already in save progress

I have already checked the following points in my installation:

• I set the memory_limit to 512M and the max_execution_time to 280 in my server settings (these were saved correctly, I checked).
• I updated Elementor to the latest version (3.32.4) and tried countless older versions before that.
• I deactivated all other plugins except Elementor.
• I deleted Elementor and reinstalled it.
• I switched to a standard theme.
• I tried to save the page as a template (saving is not possible here either).
• I activated debug mode ( define(‘WP_DEBUG_LOG’, true) ), but there were no error messages here.
• I deleted all caches (browser, WordPress, Elementor)
• I deactivated the autosave functionality using the following code:

add_action( 'admin_init', 'disable_autosave' ); 
function disable_autosave() {
    wp_deregister_script( 'autosave' );
}

Unfortunately, none of these measures solved the original problem. Could you help me out?

Best wishes and thanks in advance