Welcome @natali37,
Did you check your form with the Online validator? This is always recommended during development and before deployment, please.
To resolve a loading error on a follow-up form, first refresh the page, check your internet connection, and clear browser cache. If the problem persists, try a different browser, disable extensions, or use an incognito window. Inspect the browser console for JavaScript errors. Verify the correct form URL, and ensure compatibility with your browser. If issues persist, contact the form’s support or administrator for assistance. Additionally, confirming the form’s compatibility and checking for updates may help address the problem.
@natali37, making follow-ups to see if you could solve your issue. Did you validate your XLSForm through the online validator as advised by @wroos?