Rule out the scary explanation first
A stuck Elementor loading screen understandably feels like lost page content, but in the large majority of cases the actual page data is untouched in the database -- the editor's JavaScript application simply failed to initialize. Confirm this before doing anything else: view the page on the live front-end (not the editor) in a separate tab. If your content is still there and rendering normally, you're dealing with an editor-loading problem, not data loss, and the fix is lower-risk than it feels.
Open the browser console while reproducing the stuck loading screen. A JavaScript error referencing Elementor, a specific addon package (common with third-party widget libraries), or a jQuery conflict points directly at the cause. A blank console with no errors more often points to a server-side timeout or memory limit instead.
Common causes, roughly in order of likelihood
A conflicting plugin or a theme function is the most common cause -- particularly other page builders, SEO plugins that inject scripts into the editor context, or security plugins that block inline scripts Elementor's editor depends on. PHP memory limit is the second most common cause; Elementor's editor is more memory-intensive than the average admin screen, and shared hosting's default limits can be too low once a site has enough widgets, addons, and page complexity.
Corrupted or stale generated CSS is a less common but distinctive cause -- it tends to show the editor loading but rendering incorrectly rather than never loading at all. Elementor's own Tools > Regenerate CSS option addresses this directly, and it's a safe, reversible action since it only rebuilds generated stylesheet files, not your actual page content.
A safe order of operations
Start with the reversible, low-risk options: regenerate Elementor's CSS, and raise PHP memory limit if your host allows it (WP_MEMORY_LIMIT in wp-config.php, or a host-level PHP setting). If neither resolves it, test for a plugin conflict by deactivating other plugins one at a time on staging if you have it, starting with anything that also touches the page-builder/editor experience (other builders, addon packs, aggressive security or optimization plugins).
Take a restore point before deactivating anything on a production site you can't stage, even though deactivation itself is reversible -- it costs nothing and removes the guesswork if something else goes wrong mid-troubleshooting. WPFixAgent's Elementor-aware repair action can regenerate generated CSS directly from the dashboard, and plugin inventory tracking makes it possible to see exactly what changed around the time the editor stopped loading.