Hello,
Thank you for contacting Rank Math and bringing your concern to our attention. I’m sorry for the delay and any inconvenience this issue may have caused you.
Probably you are using some security plugin that makes that file not writable.
robots.txt and .htaccess files are two really important files on a website and having changes on them can cause damages to your sites if not done properly.
So usually security plugins (and even some hosts) make those files not writable from WordPress so a hacker or even a plugin can’t change them and cause issues.
If you are not going to modify those files, it is fine to have them as not writable, it is an extra security measure.
Looking forward to helping you. Thank you.
Hello,
Since we did not hear back from you for 15 days, we are assuming that you found the solution. We are closing this support ticket.
If you still need assistance or any other help, please feel free to open a new support ticket, and we will be more than happy to assist.
Thank you.