Hello
Apologies for the inconvenience.
Please disable the mod_security from your hosting server.
Could you also kindly check the following settings on your computer?
- Old version of PHP (we suggest to use 7.0.x minimum)
- Problems with SSL/HTTS certificate *
- Extra plugins: KL Admin Skin, AceSearch or JSN PowerAdmin or any similar which can change the appearance/behavior of your Joomla Admin.
- Low PHP memory limit (we suggest 128M or 256M)
Can you also check using a different browser as well ?
https://www.joomshaper.com/documentation/helix-framework/helix-ultimate-2/introduction#technical-requirements