Hi @rajviswas,

The short answer is, you can use the Classic Editor plugin for fixing this issue.

The long answer would be something related to the newest WordPress editor which seems to be experienced on few WordPress installations and now all.

Anyway, regarding the .htaccess bit, I’ll recommend using at least the usual/default WordPress .htaccess which is

BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteRule ^index.php$ - [L]
RewriteCond %{REQUESTFILENAME} !-f
RewriteCond %{REQUESTFILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>

END WordPress

Regards,
KDSys