site adding #tab-description to Woocommerce product page url

Hi guys

I have an issue where "#/tab-description" is automatically added to the end of a Woocommerce single product page url. See this example:

I've looked around and read things such as this post: explaining that it's a plugin incompatibility but I have tried deactivating every plugin except for Woocommerce and Domain Mapping (this is on a multisite).. No joy.

I've also read that it could be to do with permalinks not agreeing with eachother.. I do have a custom base of "calendar" for the products and did have a page also named "calendar" but have changed the page slug and also tried changing the custom base for products but neither of those worked either.

I've now run out of ideas.. I've searched through my theme code (written by me) and the plugins for anything that may be causng this but I'm stuck!..

Any help would be massively appreciated! Thanks in advance