I don’t know a lot about HTACCESS but ran into this on another site, whenever I made a custom HTACCESS file and uploaded it to the server things worked great.
But then say if I changed the permalink structure through WordPress options everything would break. Took awhile to figure out what was going on until i stumbled across this on another site.
“05. WordPress is overwriting my .htaccess file?
Yes. WordPress will overwrite your custom htaccess file if you upload one to your server and then change anything in the permalink options within WordPress, or load a plugin that utilizes these features.
This will cause your htaccess file to be overwritten and you will lose any changes you have made.”
The solution sounded like make any HTACCESS / permalink / plugin changes within WordPress first and then add your own rules to the HTACCESS file after that has been done.