Woocommerce 3.5 keeps writing .htaccess file

Hello,
it seems that since we upgraded to woocommerce 3.5, the action scheduler running every minute is launching something which overwrites the .htaccess file every minute… and sometimes even emptying it.

We disabled all others plugins… same problem.

Deactivating woocommerce plugin stops the overwriting.

We have no scheduled actions…

We protected the .htaccess file (chmod 444) to keep the site running.

We are running WordPress 4.9.8 with Impreza theme

Any advice ? is it a known bug ?