I have just tested on 2 sites. One on SiteGround and another on UKfast
Both running WordPress 5.9.3 and Admin Tools 1.5.5 Pro.
Both sites are also connected to mywpguru
Needed to add the directory access to:
Directories where all files including .php will be accessible:
wp-content/plugins/mywpguru/bfnetwork
When I press save and create htaccess file I get a message to say it is saved but then the lines I have added have not been saved. But the new lines have been removed.
If I check the server side I can see a new files has been created but there is no referrence to these new lines.
Web design and development in Reading and Oxfordshire UK.