Bug adding category

Hi,

First time user of Opencart so thought I'd get that out in the open to start with!

The site was installed by Siteground automatically and so I have no reason to think it's misinstalled, and we're running v2.3.0.2

Empty everything and getting the site setup...

1. Add a category - call it "Cat". I just entered the category name and meta tag title, although the same error occurs when I complete all / most of the fields. This category seems to add just fine in the backoffice, but it does appear twice on it's on drop down in the main nav - an error I thought might be template based and thus I'd "get around to it" when the time came.

2. Add a second category - call it "Dog", as above - just name and meta tag title.

3. Result = a single category called...

"dog > cat > cat > cat > cat > dog > dog > dog > dog > cat > cat > cat > cat > dog > dog > dog > dog > cat > cat > dog > cat > cat > dog > dog > cat > dog > cat > cat > dog > dog > cat > dog > cat > d"

See attached image.

And when then loading the front end...

Fatal error: Allowed memory size of 805306368 bytes exhausted (tried to allocate 32 bytes) in /home/handmad5/public_html/system/library/db/mysqli.php on line 24

Any idea's ?

Cheers,

Russ.

Did they manually upload the files or use Softaculous? I am not sure how reliable Softaculous is as I've never created an Opencart store this way.